How to train your hands while working with punching/ boxing bag

Touching back on earlier questions about conditioning, there really is no need to do extensive hand conditioning in preparation for fighting. The fact of the matter is that you're not likely to ever be in a fight, the fight will likely last less than a minute, and if you do have to fight, you'll have bigger concerns than split knuckles.

That said, the key is to go progressively. Initially, you're going to want to wear padded gloves and striking more slightly while learning proper technique so that you don't injure your fingers and wrists. You then move on to lighter gloves that don't reduce impact forces as much, but reduce scraping and still distribute the force of the punch by a bit. Then, you move on to cloth wraps or gloves, which still help reduce the scraping, but don't do as much to distribute the force. Lastly, you start doing bag work with bare hands. That, by itself, will gradually weather your hands to the point where you are not likely to hurt yourself punching with your bare hands without damaging the skin and nerves permanently.

And even then, if you punch someone, you're probably going to bruise/split your knuckles (if nothing else, they're likely to be moving as you're punching, creating additional friction), but you're much less likely to break anything, and you're more able to throw a few defensive punches, to prove yourself not an easy target, without injuring your hands.