The first question I ask an amateur golfer in the bunker is how far behind the ball do you want to hit it? Usually they give the wrong answer — two inches. If I hit two inches behind the golf ball, I’m going to sail the ball over the green.
Drawing a line in the sand and hitting bunker shots along that line, you’ll find that the proper distance your club should enter the sand before the ball is about 5-6 inches and it should exit the sand 5-6 inches past it.