I like to send horse archers round the back and disorganise their ranks, preferably taking out their weaker elements -such as archers or other light horses- completely. Then hit them with a frontal infantry charge, while at the same time hitting their weaker units in the rear with the horse archers. In the majority of cases, their army will rout as soon as the charge hits home. One battle, I had 32 dead compared to their 613 using this tactic.