Remember to think about what you want him to hit, and where you want that something to be. The second punch right now has more or less zero range? How would that work in a game?
Etc - you should think about such things.
If you ever decide to revamp your animation, then I urge you to use these steps:
1. draw wind-up frame
2. draw mid-punch frame (arm fully extended) <- this should be made to be as effective as possible and should also probably be redrawn from scratch. His whole body balance should probably shift slightly.
3. In-between frames! (mostly a load of overreach>follow-through frames after the punch, actually)
Yup, that's a good workflow : D