What you do in combat depends on what you are fighting.
Humanoid Opponents(bandits,goblins,ect.): Aim to take off a limb, foot or weapon hand/arm first. If fighting large groups always be back/sidestepping as not to be surrounded, face one opponent at a time trying to cripple or open an artery. I like to circle around as there are usally some archers peppering you so you can pass by them and take them out/incapacitate. If you are a decent wrestler taking weapons away from opponents is always good. If you are fighting koblods (that manage to survive world gen) or smaller sized things, charge is nice.
Night Creatures: They dont feel pain, and Cannot suffocate. They often are very hard for newer adventures, because of their speed and high dodge. Distract with companions if possible and take off some limbs. The stun will make them eaiser to hit, If you are not doing so well its okay to back off after cutting a bit, they can die of blood loss.
FB's of any kind: Anything liquid, touch it and it dies. Giant Steel lobster, run like hell. Many will have poison secretions/blood/bites. It's risky to fight those as the syndromes will ruin your day. I tend to back off and toss crap at them untill they die. Or recruit lots of meatsheilds and let them do the work and then die from the syndromes. I've killed FB's and then laughed as their blood rotted my legs off.
There are to many creatures to get into detail, but every one has its little things. so I'll run down some of the specifics I have picked up.
Megabeasts(dragons,ect.): Sheild is important, for anything with a breath weapon really, but needed with dragons. I have had some luck with spears, their scale is pretty tough, try to stun and go for the head. BC's are very tough, bring buddy's also note that if you have a weapon of lower quality it's not doing squat vs bronze. Remember to adjust charge and charge defense.
There are plenty more, but those are some of the things that I had trouble with.