A punch training exercise
Take a sheet of paper with blue tac or drawing pins in the two top corners, then bring the two together a press onto the wall, therefore creating a bump of paper, this will now be the target.
Try to focus your punches so as to JUST hit the paper.
The more you gain confidence in control separate the two drawing pins/blue tac just a little, going further apart each time until eventually you are punching a sheet of paper on a wall, but not hitting the wall.
You may find this easier if the paper is previously scrunched up