A smelter needs to be placed close to a mine.
The mine itself is not a workplace, more of a storage, which the smelter can draw resources from. Place the smelter close (see the black/green dots), and assign workers.
In the case of your first copper/tin bar, you most likely need to trade for the copper and mine your own tin. The quarry for the tin will likely be far away, so you need roads and upgrades to ensure your worker ACTUALLY does any work that day (not just spent 14h walking to the town centre for food and drinks before going back to bed). Assigning 2-4 workers with houses nearby of the smelter also speeds up the process.

For internal trading you need to have one marketplace in each zone. Once placed, one marketplace needs to "request until x" while the other market must "provide over".
If you need to transfer sticks to your new zone, the new zone must "request until 100" (thus gaining 100 sticks), while your starter zone must "provide over 500" (and will give away any sticks over your 500 supply at home). Adapt this value for your set up, obviously.
Ensure your "provide over" is lower than your map total storage, else this will have no benefit.
Maps that produce resources they don't use themselves should "provide over" 1.

You can "buy until", at the same time as "sell over" to ensure you have at least 1 plank at all times, and sell once you have more than 20 planks.
It may not always be possible to buy or sell, as the other villagers might not have a demand or supply for them and selling huge amounts of the same ware usually saturates their demand quickly.
It is a good idea to set values for buy and sell food early and check in once in a while (~yearly)

A good setup for all these values is Buy until 5, Request until 10, Provide over 20, Sell over 25 (or similar depending on the goods). This ensures internal supply and demand is met, while trading externally is balanced at need.

The Harbour itself does nothing, there are no storage or workers here, but unlocks the "global" trading network. You don't access anything extra on your map, but the market place suddenly has a lot more demand and supply of various goods, no longer only trading with the factions you can find on the various maps. Build this as early as possible for a more living economy.

When needing other minerals that are not available on your initial map, other zones/maps are useful. Make sure to use diplomacy to either take over, or be able to move in to the map, as well as discovering the resources available.
In the first scenario, I chose Zwimmen for iron+gold+stone, Coast for lead+tin, Tablelands for copper (takeover). Which way you choose doesn't matter.
The buildings required are the same as detailed in "satellite villages" as detailed below.
Don't think of a new map as "everything one more time", but a chance to make a functional village that serves a purpose. Take extra care of the specific conditions of the map (cold/heat + soil conditions + seasons).
When moving in, send all the material required for the first basic buildings. Once sent, send 5-10 villagers and let them build the town. Once the town is ready for more people, send them in batches of 4-10. Make sure they have houses and work to do.
In my case, Zwimmen had ~30 people settled, Coast ~50 (also produced clothes), tablelands ~25, Lakes ~30 (clothes production).

The word referring to a settlement on the same map as your main village, but more than 6h of walking-distance for your villagers.
In these cases, you cannot have them walk from their home, to the workplace and put in 1h of work before they return to the main village for food/drink+sleep.
Building such a small settlement requires some minimum buildings, namely gatherers hut, campfire, rudimentary tailoring table (can be skipped in maps without winters), forester's stump, then your functional buildings (usually smelters).
At a minimum, 2 gatherer, 1 cook, 1 tailor, 1 woodcutter is required and you usually want 2-4 smelters, plan your housing accordingly. The finished bars can be transported long distances, and your smelters can finish them in a days work.
If you are going for iron/gold, another woodcutter + 1-2 coal makers will be needed.
Finn torches are required if you can't build houses close to the campfire, but usually a good idea regardless.

This settlement brings very little attraction to your village, so your immigration will be lower as a result, limiting how many / how fast you can build of these or making your heavily reliant on children and long term growth.
Do a round once in a while to ensure the people working there also lives there, otherwise they waste their days away walking.
Extra tip: Name your buildings in a certain way. "Lakeside Finn Torch" - "Lakeside Gathering Shack" etc. This groups them nicely in different windows.

Early game you depend on children for long term growth. Keep this 30-50% of your population.
Around 70 people, lower this to 20-40. Above 100, around 20-25.
(UK has 17% of its population between 0-14 years, for reference, but also 19% above 65 years).
If you plan to expand to 200+, even 500+, 30-40 is a nice steady growth that should be manageable.

If your side towns are small by comparisons of your main town, avoid children, or keep them low, you can always emigrate when the population turns old.

The only (and difficult) way of finding your age distribution, is to go to population -> Census -> Humans, hover your mouse to see the population-pyramid. It should be small in top and bottom, with a big chunk in the centre. If there is a gap in any pillar, you should worry and monitor the population carefully. Age bubbles can halt your progress and have years-long consequences.

Animal population should mostly have younger individuals, not the same distribution as humans. If the population is high, but sloped from young down to old, it's stable. If there is only old individuals, it's dying.
For small populations, gaps and bumps are normal. Make sure to check which animal you are hunting for (and who eats who. Killing rats also means killing cats).

You can click at the top to see how much of each resource you have in storage.
You can also hover to see the production/storage.
HOWEVER!
You can click the resource to see WHERE it's produced, WHERE it's used and if it's used in any upgrades... Each of these can be clicked as well to find the location, so you don't need to check every building for which uses what... Huge benefit!

Your villagers will get dirty and try to stay clean. This tier 2 need carries over to tier 4 with a bathhouse, but can only do so much if your streets are filthy.
The "dirt" layer on your map that you were introduced to in the tutorial, doesn't only show nutrients in the DIRT, but also the DIRT in the streets. Anything over green is necessary for the plants. Anything over orange is a negative for your villagers.
Get enough cesspits around the farms as well as sweeping stations in the high traffic areas.

If your villagers can go through a building, it counts for a valid path.
Buildings can partly replace the streets for compact builds, just make sure to check where the openings of each buildings are and if you choose to block one, ensure that you aren't making necessary long paths around.

The amount of stored items you can have in one settlement is determined mainly by the producing building. A farm that can produce up to 50 grain will harvest until 50 grain, store that and only slightly more (if the worker picks up 5, when the storage has 48, the storage will be 53).
You can upgrade storage for the building, for example, farms can upgrade by 60, 140, 140, total of 340 (on top of the base 50), grand total of 390 storage of EACH item the building produce.
390 grain, 390 roots, 390 fruits, 390 veggies, 640 grass.
There are buildings that can store items, materials storage, root cellar and granary, but these three does not together store every item in the game. In other words, some items will not be stored in them, and storing them here requires a worker.
Items and food does not spoil over time.
The workers in the market will pull items from anywhere on the map, but only items that go over the "provide over" limit. If you set fruits "provide over 200", the workers will retrieve fruit when the map-total storage reaches 200 and store anything over 200.

Villagers die if they get too hot or too cold.
If they get too warm, ensure some shade (trees) or water deep wells if you are far from streams/lakes.
If they get too cold, ensure clothes, but rags can serve the purpose as well. The better clothes, the more cold protection, though fancy clothes are only useful for tier-progression.
Higher tier houses provide more heat and upgrades help too.
Pets provide a small amount of heat, since they snuggle up with the villagers.
A row of barns, with a row of tailor shops will quickly produce the amount of clothes you need, scaling depending on your population.
1 Tailor shop per ~75 people.
1 Dressmaker per ~200 people.

My village of ~80 people had an age bubble and died back down to 40 people. Focus on what is essential workplaces and cut way back on those who are not required. Spread out your food production.

At around 150 population, half of the population was above tier 5. Sudden drop made 90% go down to tier 2. Focus on their needs and reinforce your campfires, sweeping stations and shrines. Your villagers no longer care for kitchen and restaurants, but want campfires.
The opposite is also true: Once your villagers crave restaurants, they no longer care for campfires.

Click on a few villagers to sample their needs and focus those.

Animals wary in sizes and you can expect more meat and leather from larger animals, despite the game offering you to barn animals like racoons and rats.
Their actual meat-gain depends on when they are killed and their "energy reserve". Open the animal-info box. Health is purely if it's alive or not, but the status above will show its weight and thus its current amount of meat and leather if slaughtered.
This value is increased if the animal has plenty to eat and otherwise high comfort.
According to the devs, their expected meat-weight is as you would expect in real life. Cows and deer give a lot of meat.
If you need wool, always keep sheep, as they also provide milk and thus better than cows. The exception is with their meat gain, but is rarely an issue. Chickens are good for eggs, all other animals are "for fun" and sub-optimal, but you are welcome to play out your sick fantasy of a rat barn and cat barn next to each other and it's all served at the local restaurant.

A recurring theme in my towns, growing past ~150, close to 250, people died of cold.
Do I need more clothes? More torches?
NO! People are walking into the wilderness because they are lacking food.
Closely inspect your villagers, sort your population by health and watch where they are before dying to root out the source of your deaths.
Read my "Food" chapter to solve this issue. Logistics and placement of your food might be an issue as well.

In populations past 50, think about your total amount of calories and do not neglect your basic needs.
People falling back from tier 4-6, back down to 2-3, is usually a result of not enough food serving. Build enough campfires with a few kitchens to have them climb back up the tiers. In 200+ populations, 5-8 campfires are useful, with 2-5 kitchens. More than 1 restaurant is only useful if you want more than ~25 people in tier 5-6.

Regardless, count your calories. Each person needs ~2400 calories. Having one of each item (1 egg, 1 root, 1 fruit etc), amounts to 1757 calories. In other words, each person needs ~1 of each, +500 calories, or rather, 1.4 of each item.
Put in another way, on average, each item provides 146 calories, and you need 16.5 of everything you have, to survive for a year and avoid people walking into the wilderness for food. This is obviously simplified, but gives a fair estimate of your food stocks.
Total amount of food, divide by 16.5, must be higher than your population.

This is per day, so you can multiply by 7 to get a week (aka a season on most maps) and by 28 to get a full year.

Most large villages you want a day off and then keep a 70h work week (unless you can afford the 50h).
Balance the days evenly, 12-12-12-10-12-12-0 or similar. Making unbalances, for instance 14 0 14 6 14, or something does not mean efficiency. People get tired past 10-12h, and the 6h days mean they barely get started before going home.
Check your work loads in the employment tab. Most should sit at 70-95%. If almost everyone is over 90, with half at 100, it means you have too much going on.
If you have a lot of villagers working 2-3 jobs, check where they work and ensure they are close to each other. Starting the day at a farm and ending it by the gold mine on the other side of the map usually means a wasted day.
Assigning a single villager to 3 finn toches that are close to each other usually means efficient use.