Before you play in sandbox, you should definitely play at least a couple campaign stages. The early ones cover the basics of the game very well. You should complete at least the third stage, as you will have a firm understanding of how the game works by then. I do recommend completing the entire campaign to get more practice.

The campaign took me 12 hours, but I played extremely slowly and on medium difficulty. If you're a faster player and rush to the end on easy, you should be able to easily complete the entire game in less than 10 hours. Not only does this net you personal experience with the game before making your sandbox aquarium, but also it gets you most of the achievements along the way.

The advice here is not covered in the tutorials. If you have not completed the first few stages in the campaign, please do so before continuing as they offer the actual basics of gameplay.

I put tips here that I consider too simple for their own section.

OVER-SATURATE TOOLS AND FOOD
Every time you expand, upgrade, or move stuff, make sure there are appropriate items nearby. The costs of tools and feed is minimal in comparison to the profits you make, especially once you get a gift shop or two. It can save you a lot of prestige to make sure your fish don't die because the nearest food is a five minute walk. Additionally, the amount of food each box can put out is limited, so you can truly never have too much.

BASIC LAYOUT
Make your aquarium a simple shape thats easy to navigate and even easier to expand, such as a circle or square. Complicated layouts may make guests miss exhibits, meaning you don't get prestige. The shape I usually go with is a straight line, as there is no bonus for having complex buildings.

IMPORTANT MAIL
Your mailbox can get quite cluttered later on with all your "X has grown to size Y" emails. An easy solution to this is the important mail button. In the mail window, at the top left you'll see a little mail icon with an exclamation mark. Click that once. Now, the only mail you'll see are important messages such as employee level ups, traders, merchants, story stuff, and unread messages.

FORCE GIFT SHOPS
As soon as you unlock any gift shop items, use them! Just like in real life zoos and amusement parks, make gift shops impossible to avoid. I recommend putting one right at the entrance, and another about halfway through your aquarium to maximize sales. On top of admission, drinks, and food, gift shop income will drastically outweigh the upkeep of supplies and feed.

USE NURSERY TANKS
On very rare occasions you'll find two fish you want in the same tank, and both of their adult versions can live well together, but at some point in their development they will be incompatible. In these cases, having one species grow up in an isolated tank is a great idea. Then you can simply pick up the species and drop it in the actual tank once it's grown to a safe size for it's tank mates.

PLAY SLOW
Take your time and think about your plans, the only time limit is your own gaming time. As long as you aren't rushing full speed ahead, you'll be able to afford every expansion or upgrade, and you can avoid mistakes you may not have had you gone ahead without thinking.

PRIORITIZE HIGH SKILLS
Make sure that you tell your staff to only do jobs they're good at. In the staff management window, you can click the green bar by their levels to change their priority. Green means low focus, Blue means medium focus, and Pink means heavy focus. Grayed out means they ignore all tasks of that type. If you have a designated fixer, make sure their fix is Pink while their feed is gray. You don't want a 10 fix/1 feed stuck feeding a fish that requires skill for the whole day.

SPECIALIZE YOUR STAFF
When you level up your staff, try maxing out one skill at a time. It's much better to have one max rank feeder and one max rank repairman than two who are mid rank for each. They'll get their jobs done quicker, which lets them take care of more difficult jobs more efficiently.

JUGGLE ZONES
Staff typically have low levels to start out at, rarely above 3. You'll want to stick these people in lower difficulty job areas, start them off feeding the small tropical fish you get at rank 1 before moving them up to rank 12 manta rays and sharks. It's not good when your rank 10 feeder is done feeding their zone an hour into the day when your rank 2 feeder only has one fish fed by closing time. That being said, you will likely juggle staff around a lot when you hire new people.

PAY ATTENTION TO STATS
When you hire staff, you'll notice they have two stat blocks. One for skills such as Fixing, feed, cleaning, etc, and one for stats such as Precision, Memory, Athletics, etc. Stats provide bonuses to skills and may make a staff member with a low feed skill actually better than one with a higher skill. You can see what each stat does by hovering over it. This isn't important early when you just need bodies in the building, but later on when you have 30 tanks and only 10 people to feed them it could mean the difference between a fish getting fed every day or not.

PICK UP YOUR STAFF
Sometimes your staff take bad routes, making a detour to grab tools or food out of the way of their current path. When this happens, you may lose some prestige due to a fish looking stressful, or even dying. Feel free to pick you staff up as they make a hundred tile trek to put one green pellet in the tank at the opposite end of the building. They don't drop their items when you do this, I typically only do this in actual life or death situations since it is very micro-managey and takes a lot more effort.

One very important tip that I don't remember being explained well (if at all) by the game was staff zones. Click on the staff button in the bottom right, then click on the manage tab. Next to your staff you'll see either the name of a zone or "NO ZONE ASSIGNED". Click on that to open the zoning menu. From there you can easily paint zones for your staff, and assign staff to each zone.



Remember to rename your zones! Use something you can easily recognize which area it is at a glance. For example, in my screenshot my zones are named after their location. You can also do something such as "Cold", "Tropical", "Crustacean", "Sharks", or whatever works best for you.

Make sure to assign appropriate staff to each area. I typically use one or two feeders, and one fixer for each area, depending on how big the zone and the type of creatures. Zones with lots of tanks or fish that require skill to feed would require more feeders than zones with few tanks and easy to feed fish. Animals that require supplements also take a while to feed and you should keep that in mind when assigning staff.

Make a "Cleaning", "Gift Shop", and "Talking" zone. Assign staff with high priority on these skills to this area. I will have a few staff run ONLY cleaning and mark every tile that guests can walk on. I also typically have one gift shop with one or two employees stocking it where only they are allowed in. Talking employees also seem to get lost and occasionally miss talks if they aren't assigned to their podiums.

Once you have your zones set up and staff assigned, feel free to rename your staff. Click on them to open their personal window. Double-click their name to change it. From there, name them something like "ZoneName Feeder" or "ZoneName Fixer" so that when you level them up, you don't need to worry about forgetting what they do.

During gameplay, you will occasionally receive mail asking if you want to purchase or trade animals or fund a supplier. You should always do these if possible as they will grant you access to fish and decor either earlier than normal, or at a much cheaper price. These are not limited time offers, and there doesn't appear to be a limit on these offers you can have, so declining is never wise.

Sometimes you just get fish early, sometimes you get five pieces of decor for the price of one. No matter what the deal is, you'll be getting more prestige faster and cheaper than normal by taking these deals.

Pay special attention to any that say "supply"! These unlock the ability to purchase that fish/decor/tech, and are the only way to get some of them in modes with limited availability.

GUEST NEEDS
Keep an eye on your guests, see how far they get through your aquarium before they get hungry or tired, and consider making a small rest area. When building vending machines, seating, and bins, you'll see a green area on the ground. This highlighted area is how far guests can detect these machines. You should make sure every tile your guests can walk on is highlighted for each, if you don't, you will lose prestige. Even one tile could mean guests get frustrated and leave, losing you prestige.

ARROW YOUR FLOORS
Guests are extremely stupid. They lose their way very easily, and will turn around and leave if they can't find their way around. You should always overuse arrow signs. Like the vending machines, the highlighted area when building one is the detection range for guests to see the arrow.



This screenshot is old, back when arrows only reached 3 tiles out. Their detection range has since doubled to 6, and guests will follow the indicated direction 12 tiles before getting lost. This means you can have an 18 tile gap between arrows before guests get confused and lost, but I still place them with only 6 tile gaps just in case.

Prestige is how you rank up, and you'll need lots of it at higher ranks. Getting into the exact numbers takes way too much time and effort to calculate and test, so I'll just give a quick crash course.

HOW TANKS GENERATE PRESTIGE
Whenever a guest views a tank, the game generates a random number for every unique species in the tank. If this number passes the chance threshold for a species, then that species will generate prestige for that view. You can check the chance by clicking a fish and hovering your mouse over the prestige amount. The Azure Demoiselle has a 32% chance to provide 1 prestige. To improve the odds, add more of that same species to the tank. 5 Demoiselle has a 72% chance of earning you prestige, and 14 has a 100% chance. (I tried to figure out the formula to help you always get 100% for each fish, but it appears to be different for every species.) Please note that this only increases the odds prestige is gained, it does not increase how much prestige is earned. Larger fish also tend to have a higher base percent chance than smaller ones. Fish that grow, such as the Panther Grouper, have a higher chance at their larger sizes, and may increase prestige gain when max size. All of this extends to decor as well.

DON'T RE-USE FISH
Make sure all duplicate fish are in one or two tanks to minimize double-dipping into prestige. When guests see the same species multiple times, they get bored of it. A second viewing earns no prestige, but the third viewing and each beyond actually decreases your prestige. Necessary decor that provide stuff such as plant or rock points to a tank can be used freely in as many tanks as you want, they do not cause negative prestige.

LISTEN TO GUEST THOUGHTS
Click on your prestige bar to open the prestige window, then on the guest thoughts tab. This brings up a list of thoughts your guests have. This shows every production and loss of prestige in your entire aquarium over the last day. Scroll to the bottom to see all your prestige losses and try to get those sorted out. Make sure you have enough staff set to clean, that you have enough rest stops, that guests can't get trapped from one-way doors, and that you don't use duplicate fish.
NOTE: Guest Thoughts tab seems to be currently bugged and may freeze partially or entirely. If this happens to you, a simple reboot of the game should fix it.

Podiums are very important, they allow you to gain all three of the main points with little to no extra cost. Typically, I don't struggle with ecology or research points, only prestige, so I only set podiums to prestige value talks., however, feel free to earn ecology and research points if you want to get a certain fish/item faster.

DEDICATED TALKER
Same with all other staff types, you should always have one or two dedicated talkers. Staff with high talking skill will get through their talks much quicker than those with low talking skill. One should do you fine, but if you have a large aquarium, or want multiple talks at the same time, two talkers is also a good idea. I would avoid going higher than two though.

MIC STANDS AND TRAVEL TIME
Frequently, a talker may be late to a scheduled talk, which would throw off the entire schedule. Make sure to put them in a zone with only access to important areas for their talks such as podiums, mic stands. Don't set up travel routes as they should already be taking the shortest route to get from one destination to the next. Be sure mic stands are in staff rooms next to the podiums, or are in the path between podiums. One mic stand is needed for each talk per day. This is by far the most micro-management job in the whole game due to how slow staff tend to be. Unless they can consistently arrive on time to every talk, consider picking them up and dropping them in front of mic stands and the podium to save time and not throw off the whole schedule.

TALK DELAYS
Never have a talk set to 0 days in between. Just as guests tire of seeing the same fish over and over, guests get bored hearing about the same fish every single day. A 2 day delay between your talks is usually the best, and if you set them all up right, having 3 unique talks every day all on a 2 day delay will be a great source of prestige.

FISH SIZE
Sometimes when fish grow, their talk rewards increase as well. The talk your podium has will still give the old point value until you set it to give the new one. Zebra Moray 10 Prestige is an entirely different talk than Zebra Moray 11 Prestige. These little points add up once you consider you'll have 30+ guests at every talk.

LOCATION, LOCATION, LOCATION
Make sure to cram your podiums into high traffic areas. Near bathrooms and vending machines, in a corner with tons of tanks, next to a massive tank, anywhere you have a lot of guests at any given time. Guests will stop to listen to talks when they get close to them, even if they're doing something else. If one area consistently has 60 guests at one of the talk times, place a podium there. Or you could just pause before every talk and move every guest to the podium so they hear it, but that's just rude.

POSTERS
Posters work similarly to podiums. Slap them next to a tank, preferably in a high traffic area, and they provide you with a resource! This time, ecology and science points rather than whatever the species offers. Unlike podiums, you don't need staff to man them. You can only have one poster per tank.

WHICH POSTER?
The type of poster you use produces the corresponding research point. Regardless of the contents of the tank, a science poster will produce science, and an ecology poster produces ecology. You should only ever use the type you are producing less points of.

HOW TO POSTER EFFECTIVELY
The science poster produces more science based on the number of survival requirements for all the species in the tank, while the ecology poster produces more points based on the number of species. More complicated species, like sharks, with lots of survival needs are more effective for science posters, while less complex species, like clownfish, are better for eco posters since its easier to cram in more species. Either way, just add in a handful of unique species to the tank and you get more points.

POSTERS NEED UPDATING
Similarly to podiums, when you attach a poster to a tank, it locks itself at that point value. Even if you add in four new species, it produces the same amount of research points, even when it shouldn't. The easy solution for this is any time you introduce new species, simply detach the poster and re-attach it. It will update to the proper amount.

Starting at prestige rank 5, you will begin to unlock equipment for your staff. You can equip your staff with certain types of equipment to make them more efficient at their jobs. You will need the Freshwater Frenzy DLC to use staff equipment.

BACKPACK
The backpack doubles the staff member's carrying capacity for food from 50 to 100. Equipped staff can still only carry one type of food, but it will save trips to back and forth from the supply station. This is useful exclusively for areas with high food requirements.

SNEAKERS
The sneakers increase the staff member's athletics skill. This allows them to run around your aquarium faster, effectively shortening any distance they need to cover. This is perfect for talkers and cleaners since no other equipment works well for them. though any staff member can make use out of it.

TOOL BELT
The tool belt allows a staff member to repair simple parts faster, and can be used instead of a repair kit. This will save your fixer staff time as they no longer need to run to and from tool stands. This has no effect outside of the fix command.

FEEDING STICK
The feeding stick increases the staff member's feeding speed when feeding animals that require skill. More complex animals such as sharks and turtles require skill to feed. This is best used in sections dedicated to these types of animals. It has no effect outside of this use.

If you have any additional questions, in case I explained something poorly, or not at all, feel free to ask in the comments below. I'll investigate as well as I can to help out fellow players.

None of the achievements are difficult to acquire, the toughest being Sandbox Trials - Limited. Of the fifteen achievements, 10 are obtained merely from completing the campaign, and the rest can be obtained merely by coincidence during the campaign. In case you missed one, here's a quick guide on getting them all.

Have 1000 guests enter your aquariums.
Easily completed early on. Should have done by first three stages in campaign, will be done before the tenth. Can be easily completed by leaving your game running while doing something else.

Grow 50 animals to full size.
Again, easy to complete. Should be done by stage four or five in the campaign. Can be easily done by making several tanks and placing growing fish in them and setting up staff to take care of, then leaving your game running.

Name an animal by opening its window and double clicking its name.
Another super easy one. Explained by the achievement.

Buy 1000 animals.
More easy achievements. The only achievement I didn't have complete by the time I finished the campaign. Just make a max size mega tank and spam it full of clown fish until you get the achievement.

Complete 5 trades.
You guessed it, easy....again. If you didn't complete it already in the campaign, boot up a sandbox and set it to quick start, you should receive trade requests from collectors very quickly.

Sandbox Trials (Standard / Limited / Completionist)
These are the three hardest achievements to get. If you completed campaign stage 10, you should have enough of a handle on the game to complete these easily. Just boot up sandbox mode, click the preset, make sure you're on normal (or hard) difficulty, and hit start. These will take a few hours.

Complete 30 Side Objectives
If you don't have this complete by the time you finish all the Sandbox Trials or campaign stages, simply boot up a Limited sandbox and do all the side missions you can. Side missions are the ones that get tracked on the side and have rewards such as increased base prestige, trades and buying decor/animals through mail is not a side objective!

Have 1500 prestige income from decor and paint
If you don't have this complete by the time you finish all the Sandbox Trials or campaign stages, just load one of your saves and make sure you have each type of decor placed somewhere.

4000 daily revenue from food, drink, and gift shop sales
If you don't have this complete by the time you finish all the Sandbox Trials or campaign stages, boot up one of your saves and slap down a ton of food/drink stands. If that doesn't finish it, squeeze in another gift shop and repeat until completed.