Greenside bunkers are not happy places for most golfers. Chunks, skulls, shanks—a lot of bad shots can be traced to a faulty setup, usually with the ball too far back and the hands too far forward. That leads to a steep crash into the sand and an ugly result.
The big swing fault I see is cutting across the ball with an out-to-in club path (above). You can get out of the sand this way, but it's difficult to hit the ball on line. You'll tend to pull it or put a lot of sidespin on it.
If you want more-predictable results, do the opposite. Play the ball up in your stance, in line with your front foot. And instead of pushing your hands forward, drop them back so the shaft is vertical or leaning slightly away from the target. That'll help the bounce on the bottom of the wedge slide through the sand.
As for the swing, I like to see the club come into impact from the inside and go more down the target line (below). A good test for that is where the sand goes: It should fly toward the target, not way left. Look at your divot hole, too—you want long and shallow, not a bomb crater.
Draw two lines in the sand when you practice: one to represent your target line and another extending toward you at 90 degrees. Place a ball where the two lines meet, and take your stance with your front foot on the second line (below). From this setup, you'll tend to enter the sand two to three inches behind the ball and slide the club under it. Perfect!
Butch Harmon is at Rio Secco Golf Club in Henderson, Nev.