I play on expert. It takes me awhile to build up my all cavalry assault force. My usual strategy is to conquer a good number of easily guarded territory then to start building up my assault forces and my defense forces.

Assualt forces consist of 12 heavy cavalry and 4 light cavalry (for riding down other units of light cavalry.

Defensive forces consit of 4 units of heavy cavalry, 4 units of Pavise Arbalests or best archers available if they are not available, 4 units of artillery and 4 units of the best spearmen available.

Attack Tactics are simple. Manouver the enemy into a position where they are easily flanked or better yet, caught bettwen my forces.

Defensive Tactics are find a nice position, rain down artillery fire on the enemy while they close the distance. Use the archers to soften them up, maybe even driving some units off. Use the spears to pin the attacker in place and of course flank them with cavalry.