Nicholas Brag recently wrote an article on punting techniques and I thought it was worth sharing:
Overview
Punter is one of the most difficult and least rewarding positions to play in football. Punters are expected to kick the ball well on every attempt, no matter what, and one dropped ball or one botched play can result in a lost game or even a lost job. Punting techniques vary significantly based on what the punter is attempting to do with the ball.
Open-Field Punt
According to longtime NFL punter Ray Guy, the open-field punt mixes a combination of distance and hang time, with distance taking a slight backseat. The reason for this is that a punt that hangs in the air for a longer period of time allows the coverage team more time to advance toward the returner, thus decreasing the chance that the returner will have a big-play return. This punt is performed by slightly raising the position that you drop the ball, or holding the ball a bit longer than you would for a line-drive punt.
Coffin Corner
A coffin-corner punt is when the goal of a punt is to place the ball as close to the end zone as possible before going out of bounds. This is typically done when the line of scrimmage is at or around midfield, allowing you to aim your punt in a diagonal motion. This punt can be performed in one of two ways. You can drop the ball sooner than normal, resulting in a low trajectory kick, and step in the direction of the punt. The other option is to drop the ball at the normal time, resulting in a long, high punt, but aim to drop the ball slightly off of one side of your foot, thus resulting in an angled kick.
Rolling Stop
When there is little threat for a return and the opposing end zone is 50 to 60 yards away, a punt that is designed to stop rolling or bouncing just before the end zone is a viable and effective option. This punt is performed by adjusting your release point and force behind the kick to match the amount of room you have before the end zone. A longer kick will need to have a lower line-drive trajectory, and a shorter kick will need a higher, looping trajectory.
High and Short
Teams sometimes will be forced to punt from its opponent's 35-yard line depending on the situation in the game. During these times, the goal is usually to punt the ball as high into the air as possible, with the ultimate result being the coverage team catching or downing the ball deep inside the opposing team's territory. This type of punt is done by releasing the ball as late as possible, resulting in your foot making contact with the punt at it's highest point, which causes the ball to fly high into the air with little distance.