Most people arent particulary familiar with the treaty style of play. Especially when you're jumping from supremacy to treaty games. Treaty involves particular builds for particular civillizations and to become a good treaty player, you need to have an understanding of the civillization you're using.

But the most basic thing you need to do in treaty is make up your economy first, advance in ages ASAP, hit the total 99 villager count, and then start training your army.

Here's some pointers to help you start your treaty career. They apply to all treaty modes (treaty 20, treaty 30, treaty 40) :-

~ Put more villagers on the resource for which you have gotten the market upgrade. If you have done the food upgrade from the market, then put more villagers to food since they will gather it much faster.
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~ Get market upgrades only for the resource you need.
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~ Always have a villager in que. Keep villager roduction constant.
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~ Get to age 3 ASAP ( as soon as possible ) and make 2 more Towncentres and have them make villagers as well.
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~ Make at least 2 to 3 of each barracks, stables and artillary foundries to get out more units in less time when the fight begins.
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~ NEVER delete your villagers. You need all villagers to be gathering resources. Just send 3-4 villagers to make forward base and walls when the fight starts.
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~ Always have a combination of units in your army. By having more types of units in your army, you can counter your opponents army and yours wont be countered easily.
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~ Have at least 3-4 culverins in your army to take out your opponent's artillary units from a safe distance.

ALL CIVILLIZATIONS HAVE A SPECIFIC BUILD ORDER BUT THE ABOVE MENTIONED POINTS ARE THE BASIC STEPS TO BECOMING A BETTER TREATY PLAYER.