Well, the best thing to do is untween the frame BEFORE the fist hits its mark. On the frame where the fist connects you should ad a punch trail effect. This will make the punches seem like they have more impact. This works with kicks as TIPS ON ANIMATING FOR NO REASON. well. You should also move the camera on the punch trail frame. I prefer to have my figures all the same color so it blends in more. Make sure that every limb is always moving to. ‘‘This will give it a reall smooth effect.