Lean left, set club: Keep your weight forward and hinge your wrists fully.
A greenside bunker is the one place where you want to make a very vertical backswing. If you don't, bad things can happen, like hitting too far behind the ball or skulling it over the green.
I often see high-handicappers using the same around-the-body swing in bunkers that they use from the fairway or tee. Rarely are they able to control trajectory or distance, because they don't have a consistent entry point in the sand. This can turn a relatively simple sand shot into a disaster.
Getting the club up quickly on the backswing requires an early wrist hinge and a full shoulder turn. A steep backswing sets up a steep angle coming down and lets you make use of the bounce on the bottom of your sand wedge. Keep more weight on your front foot throughout the swing, and don't forget to accelerate through the sand to a nice, full finish.
TIGER WOODS writes instruction articles only for Golf Digest.