Help! I suck at this game on hard.

A few months ago, someone mentioned aoe2 DE to me and I bought it. It's still a great game.

I play solo mostly against the AI. Usually choose a random map, max out the enemies, and make one an ally. Fast forward a bit. Out of nowhere, one of the enemy's is rushing me with this huge army.

I usually am no where near ready to defend!

Haha. Any tips? I can usually beat all of the other AI Sims to the first age. After that, they pass me up.