Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Aim for experienced enemies first with your artillery to soften them up.
Charge an inexperienced unit with your cavalry and you might make them flee.
Send your general to your most immediately effective unit to boost its morale.