Punt returner is not that hard a position. You stand on your own 10 yard line. If the punt is over your head waive your hand for a fair catch and block so they can't down it behind you. If you can catch it you do. Then you can try to run while securing the ball. If it is in front of you run up and catch it. You need an inner clock to gauge how high the kick is and whether you should fair catch it or return it. But, that's about it.
