Gather as much non-renewable food as logistically possible before transitioning to farms. That way the wood you would spend on farms can be spent on buildings, upgrades and units instead.

When feudal (age 2) rolls around you start to slowly transition into farms as your villagers finish off or saturate the other food sources. By castle age (age 3) on most maps you'll be completely transitioned into farms.

Some of the strongest plays you can make in this game are when you are an age ahead of your opponent. It's a window of opportunity that can be very small. But made larger by preparation, military harassment and playing as efficiently as possible from the start. I'll list a few common ones:

Feudal archers to pressure their economy. Turn them into crossbowmen and upgrade their arrows the moment you go to castle age. Castle age crossbowmen will quite easily handle anything they face at this time.

Castle age knights. Fast castle into knights is an extremely popular strategy. Knights can even be played off the back of that archer/crossbow strategy, but at the cost of a slightly slower castle time. For some civilizations, the knight line of units is their end-game unit. So investing in it as soon as it's available pays off for the rest of the game.

Trebuchets. This one can seal the game if done right. Have a forward castle built as you are going up to Imperial age. As soon as you get imperial make the Trebs then go destroy their key buildings while supporting the trebs with your army. Some civs can age up sooner and so their game plan will be to devastate their opponents during that larger window.