The bunker shot should be the easiest shot in golf, as it is the only shot were you don't have to hit the ball. Check out this cool high speed video of a greenside bunker shot. First, notice how open the clubface is at address. This allow the club to bounce through the sand. If the face is too square at address it will dig into the sand too much at impact. Also, notice how the club works straight back and works up on a steep plane off the ball. The club needs to work steep off the ball. If it works back too shallow your arc will be too shallow and you will either hit too far behind the ball or catch the shot thin. This is a great angle to see how the golf club exits through impact. Notice how the club works down the line toward the target, not across the target line. I see too many players swinging too much across their bodies in the bunker.