To block punts, its easier to turn the offsides penalty off to get a head start on the offensive line. Choose a corner or a running back (someone that is fast enough and tall enough) and do one of the two; blitz the kicker and tackle him, which takes yardage off your opponent's rushing yards in the game, or jump and block the kick. This is not a play that works all of the time. However it usually works in the punt return play, and not the punt block play. Also, it never hurts to use a little play action once every series or so.