Hmm, killing people doesn't mean you understand anything you do.
But the question is: who are those "enemies"?
infantry: keep behind your teammates, anticipate the enemies attack and then stab "around" your teammate while the attackers block is down
cavalry:
1. point your pike at them, if they aren't suicidal, they will go somewhere else.
or
2. dont point at them, only look around with ~ (or whichever button you use) and kill them, when they think you're an easy target and try to kill you.
for aiming at horses: aim low (at the chest), as they can simply downblock if you aim at the head/neck.