I use the same strategy for pretty much every battle. I base my armies around the spear:
6 units of the best spears i can get
3 units of heavy cavalry
2 units of sword/axe infantry
4 units of Missle Infantry (usually hybrids so i can use them to reinforce weak spots)
1 General (additional to the above, he only joins the fight if its absolutely necessary)

I line up the spears, place the missle behind and the sword/axe on the missles flanks to protect them. The general goes behind and the cavs to his flanks.

I slowly march my force forward, sending my cavalry wide when im near the enemy. I stop my infantry when im close to the enemy (about javelin throwing distance) and move my cavs round to the enemies rear (out of missle range).
At this point the AI usually charges straight into the spears (Note: i never charge the AI. If they dont respond, i march closer) and i simply wait a couple of minutes for the mellee to really get going then hit them in the rear with my cavs and send the sword/axe inf into theyre flanks. If my lines thin too much, in go the missle inf.

Works well enough for me, even though casualties are usually reasonably high among my inf.