Get a partner to stand about 10 yards apart from you.
Try punting the football to each other but under control. You want your partner to stand still without moving and catch your punt.
You will kick about 25% of full power, but still focus on good punting form.
Once you get that accomplished, back your partner up 5 yards and do the same thing.
This is good for control of the ball and also lets you get a good feel for the ball on your foot.