New player

So recently i started to play my childhood game again, i prefer to play as persians ( war elephant) most of the time i play 2v2 or 3v3 sometimes even 4v4 (depends of how many friends are online) the problem is that my economy is good until i reach castle age after that i get behinde in economy for 2000 poins minimum and that leave me to enemy to stump me and lose a game really soon. Any tips on how to survive until imperial age. Even if i make any cheap unites enemy stomp me with there elite units. Leaving me open for attacks. I watched videos on youtube tried to get half of populations only of villigers. But still if i dont get any army i get killed easy. Hoe to survive that? I even make walls just to be destroyed by trebushetd. Any tip will be helpfull. :)