Hitting Soft
One of the hardest lessons I had to learn in the many hard lessons of boxing, was how to hit soft. Young fighters always try to throw every punch as hard as they can. The problem with this is that they leave themselves open, and they put their opponents into a defensive shell. For me, it was almost impossible to pull the second punch in a combination so that I could put more force on the third (or fourth) punch. Yet pulling a punch serves a double purpose - it causes the opponent to think he has the space to throw a counter (and thereby leave an opening for the big punch), and it allows you to get better leverage for your big punch. I got to where I could do it on the heavy bag, but it was always difficult for me in the ring.