Punching is all about velocity and the force you can apply at that velocity. You want to be somewhere in between the force of a heavy bench (very low velocity, high force) and the speed of light jab (high velocity, low force).
For max damage and wrist strength you should aim to make contact with the knuckles of the index and middle finger. And keep a tight fist. The tighter the better and believe it or not but a strong crushing grip will increase the damage of that fist.
For a bouncer a punch is important, but I would say that wrestling, judo, jiu jitsu is up there too. You don't necessarily have to punch someone hard, or punch at all, to subdue and/or fuck them up.
Look into some of the systema fighting by Vladimir Vasiliev. That guy can destroy you in ways you can't even imagine. Alot of it is close quarters, multiple attackers, attackers with weapons, and just about all the time you appear to be at a disadvantage against them. I have 2 of his dvd's and I've watched them about 12 times each!
