Sorry this is text only. Don't give up, im sure its worth your time. Give me a vote if you get to the end and think i was right. I assume you have read some other guides or tips so i wont explain all the basics.

You can see my games in practice on my youtube channel: arjensmit6684
They wont all be executed equally well, the games represent the learning process i went trough before writing this. Check the upload dates, watch the newest.

Edit: updated video, the video now contains a lot more information and explanation, maybe even more than is written in this guide.

During the expanding phase, dont just blindly keep your spending at 100% food. Every turn, look at the tech tree, see what techs you would like to buy next turn and how much science is needed. Also see what you would like to do with the food you are projected to have next turn. Basically plan the entire turn ahead.

During the very early turns, you may spend 10 or 20% on science sometime as it costs you only 1 or 2 food and allowing you to buy a flagging tech that will save you that same one or 2 food next turn and provide more benefit later. Its even ok if it doesn't pay back the entire food investment in one turn if you still have enough food to place all the flags you want to.

As you progress trough the expansion phase, you can gradually spend more and more on science.
After taking a bunch of tiles, you may get to the point where spending money on science can get you a yield tech. Very early game, the resources can be values as 1:1:2. So again you can calculate if its worth to take science at the cost of food for such a tech. For example, you sacrifice 1 flag and thus 1 tile for a yield tech. If the yield tech gives you significantly more than the tile, its possibly a good idea. If it's about even, its better to choose the tile especially if its contested. (and you think you can defend it)

As your food per turn increases, you also get to the point where you get the opportunity to build a city. Notice how much of a discount it gets you on flagging tiles. If you are far away from your capital, building the city may cause the next tiles to be flagged to cost like 5 food less each. If your city costs 25, thats just 5 flags to regain the investment. You may not regain the entire investment in a single turn again, but if you regain much of it in a turn, its probably a good plan to do it. As long as it fits in your grand strategy and you are not giving up on contested lands.

A common habbit (And advice in other guides) is to split the game in phases:
1: Expand all you can
2: Get all the yield techs
3: Get the waste techs and buy units
4: Swich to military spending.

In previous sections i explained you should gradually move from 1 to 2. Now i tell you to gradually move from 2 to 3. If you keep focusing on expanding and yield techs until you have them all, you will then get into a rather long period where you are spending all your gold on the waste upgrades while having nothing better to do with your science and food than just buy power techs and upgrade cities. Now i am in no way saying those aren't useful, but they are not your top priority and should not be costing you time.

So after you picked the low hanging fruits on the tech tree while flagging all contested lands, but still needing some of the less efficient yield techs and some uncontested tiles, you get to start spending money instead of converting it all to food or science. Now many wait to buy a unit until after the AI has bought one, seeing it only as a necessary defense. Its good to note however that having the first unit out can be used to take first blood, grabbing some tiles. If there are key strategic tiles to take (for setting your defensive border favorably), its good to consider doing so.

Note that at this stage, everyone has limited wealth yield. Buying the first unit will cost all the money you have and can be more than your annual yield (you saved some from previous year). So when buying the unit, you have little or nothing to spend to give it power. You can only do that next turn. For the AI however its the same. So you buy your unit and move it to his border with just 1 or 2 power. He has no unit to stop you, so on the next turn you will have his tiles threatened with your lone and weak unit. Now your opponent quickly buys a unit, but has little or no coin remaining to strengthen it. You however have the ability to make it 3 or 4 strength for 15 or 30 gold respectively. The threatened tiles will be yours. This can often be 3-4 tiles and the price you payed for it is 55-70 gold with a unit to keep. That gold in food would be around 30 food, probably also about 4 flags. But now you have a unit to keep and some key strategic tiles taken from an enemy.

Fortunately the AI is not smart enough to do the same, so no worries if they have their unit out first. They will not put all their money into it the next turn.

You have flagged most of the tiles available to you, you have yield techs for all terrains you have more >5 tiles of. And your first unit just captured a few key enemy lands. The enemy bought a unit as well and they are angry. We live in a changed world now, humanity took up arms, peace is off the past.

The AI is fortunately not smart enough to be angry. They play reactive. If any tile is threatened, it will react and defend, then move to the next place to defend. Until either they have to few guys to defend, or more than they need, and they will attack some enemy tile.

If you do the same, you'll end up threatening them while defending against them and you get caught up in this tit-for-tat without a winner. If instead you place your units 1 tile away from the border, they can also defend your border and it wont be threatening your neighbor. They might go and bother another neighbor and get caught up a bit in there. Now they move a lot so surely they will come back to you as well, but you can minimize that by not threatening them.

Using your combination of city power, terrain power techs and your units, you try to defend while spending as little on military power as seems safe. Instead you spend on waste techs and more units. Every turn, consider how much military power you need to be safe. All the food and science on cities and power techs also helps you defend. Keep in mind the enemy might increase his power during this turn, so be on the safe side. What you need gradually rises. Keep an eye on the world map though and be ready to take advantage of a beneficial situation or to interfere and influence who else might be winning if you can or must. If for example a neighbor is losing hard, you may want to grab your share before another takes it all.

Coin waste reduction is top priority. Food and science you do with left over bits of gold. Try to hold off on the final coin waste reduction tech though until you got the quest that reduces it to 0 if you buy the 3% one. There are also quests for buying the final waste techs on food and science but those are not important since you will not be turning gold into food and science anymore anyway.

The military power waste reductions are bought when you reach certain levels of military power. This is because due to rounding, the next level up has no advantage over the previous one before you reach this level of power. And then when you do reach it, the fact that your waste actually goes down when you buy the waste reduction reduces your power loss for spending the gold there.

Buy 65% when you reach power level 3
Buy 55% when you reach power level 5
Buy 50% when you reach power level 11

We also want to have gotten the quest of 1 unit cost reduction for reaching the last level before we buy it.

As you are defending, you gradually need to spend more on military power. With some luck you had time to buy most of the non military waste reductions and a nice number of units before you had to move the military power spending slider almost all the way up. More units is better, quality over quantity. The price however rises fast, so you probably are able to buy about 3-4 units relatively quickly with the spending slider low and the price affordable, but than the slider needs to go up. We keep trying to buy more units though. It is now end game, our mindset changes from a defensive one into an offence one. A good offense in Ozymandias starts with a good defense though. Having a good defense with strong cities and power techs gives your units more freedom to attack.

We keep our power level at the minimum needed for defense. This is what we consider the base level. If you just keep the slider at 100% while you have money to buy for example 5.5 power levels each turn, it will just alternate between 5 and 6. And as we will see, that is not good. Not only because we don't properly control it, also because it is inefficient.

At odd levels, we waste the same amount as at the lower even levels. So we pay the same to remain steadily on level 9 as on level 8. Both levels have 4 waste on either 50 or 55%. Hence we want to be at odd levels. If we change levels too quickly, it can also cost us more than to remain on the same level because you have to buy back the level more expensively than what you gained from giving it up. This is the case if you go down in level to an even number and then back up again. You simply lose more than you gained. You think you are saving, but you are losing.

Going down for 1 turn to an odd number does have a small monetary gain. Dramatically lower than what you might think though. It is barely worth it for 1 turn. For multiple turns of course, the gain for lowering the level increases. On the upside we also want to go to odd levels and we have the benefit that we get a partial refund when we come back down again since we went up to a level that leaves us 1 more power after waste.. We always go up and down in 2 though for maximum waste efficiency.

Since going down for a single turn is not worth it and we will find at least some of our lands threatened nearly every turn, we remain at the lowest odd base level we think is enough for defense most of the time and we don't go below that even if we rarely think we can. From there we increase by 2 or even 4 when needed or desired for either offence or rare defense situations. When we see the fall back to base time periods become too short to be worth it, we upgrade the base level to the next odd number.

If things are going well, we are saving money each turn we are at base level. Having a little bankroll going is what enables us to make short power hikes above our yearly income levels possible. We also use it to buy more units when we can without dropping below base level.

Finally, we get the quests or whatever they are called, and in late game they often allow us to buy temporary military power with resources other than coin. They are great. Don't have your quest log cluttered with silly quests to threaten 8 spaces or have the most of some terrain type which means you already won the game when that happens, store military boosts there and maybe a victory point wonder.

The low ones for long term, like 1 power for 4 turns, i just use right away and lower my slider to turn them into coins. If they cost too much to use compared to what you save, then don't use them, replace them. Keep in stock 1 or 2 of the more power ones for short term like 3 power for 1 or 2 turns. These can be used to break the enemies you're stalemating with all the time. Use them on top of a spending hike to reach base level +6 or +8 to land an effective attack on your neighbors.

Another way to make your attacks succeed is by having them be synchronized. You don't want to be threatening a few tiles every turn while unsuccessfully trying to win the few tiles threatened in the previous turn. The enemy will just move from one to another and defend them easily. You want to threaten as many lands at once as you can so that it may be hard to defend. Its especially great if the enemy is also attack from another side.

So keep your units mobile. When an enemy permanently threatens one of your lands, you only need to be there every other turn to defend it. One unit can defend against 2 permanent attackers. The same is true the other way around. So when you threaten an enemy land, if you don't think you will be able to take it, don't try, move to threaten another land. If you just defended an threatened land, don't stand there preventing it from coming under treat again, go threaten some land yourself.

This will already cause your attacks to be more synced simply because your units are now threatening enemy lands much more often. You don't need a lot of power to threaten lands, so this is fine at the base level you need for defending. Once you spot the opportunity to take something, either because the enemy is overwhelmed by more attacks than he can defend against, or because you can simply over power him even if does defend, hike up the power level and go for it. Then back down again until you see the next opportunity.

Look at the map, the positions and relative powers of players and plan accordingly. Lets take the Near East map as an example.

The 2 easy tribes, Egypt and Mycenaeans in the west will always be dominant on this map. You need to keep an eye on them and try to keep them balanced as well as you can. If one gets dominant over the other, there is the risk he will run away with victory.

You can balance them by choosing whom to fight.
For example, The Blue Hittites border the yellow Mycenaeans who tent to be dominant. If the Mycanaeans are dominating Egypt, you want the Hittites to fight them to keep them in check. On the other hand, if Egypt is dominating Mycenae, you don't want the Hittites to fight Myceneaens so they can fully concentrate on keeping Egypt in check.

If you are bordering the Hittites, you can choose to threaten them, which keeps them busy and away from Mycenaea. Or you can choose to passively defend against them which will send them to fight the Greeks. This works more or less in a chain reaction so you can influence the entire map by choosing whom to fight.

Alternatively, if possible, set yourself in a position to fight the AI that is most likely to take the win and take him down yourself.

Using cities and power tech, try to build a strong defense on one side so your units are free to attack the other side. Try and make this efficient by planing the shape of your empire around cities during the expansion phase.

When playing Canaanites on Fertile Crescent for example, it is great to move north and grab any plains and river tiles you can there. They are paramount for your early food. In the long term however, you can accept that you will lose those tiles and you will defend exactly at the border where desert goes into plains. You place your cities 1 tile away from this desert border and you buy only desert power. This sets you up for a great defensive late game and losing those few river tiles there doesn't matter much when your have 50 desert tiles with all yield upgrades.

Having your defenses secured like this gives you freedom to use your military units offensively where you decide to. While i explained before to be aware of the shifting powers on the world map and how to influence them, i usually have a plan in early game whom will be my first target for an offensive war. So i will spend all my food to grow the cities on the other side of my empire so i can passively defend that side and have little city defense at the side where i choose to attack.