1. Weaken your grip. The V's formed by your thumbs and forefingers should point, not at your right shoulder, but at your chin or even a little left of that
2. Play the ball well forward.
3. Widen your stance slightly.
4. Stand a bit farther away from the ball.
5. Set your hands very low.
6. The shaft should not be vertical, but should lean slightly away from the target ~ what's called a "weak shaft" with the butt of the club almost touching your right knee.
7. The club head should not rest on its sole, but on the edge of the flange.
8. The clubface must be wide open.
9. Your knee flex should be greater than normal, and it's critical to maintain the flex throughout the swing. If you straighten up out of your knee flex, you'll blade the ball and hit a high velocity line drive.

THE SWING

The correct swing for this shot is very much from outside to in. If you imagine a line going through the ball of your feet, parallel to the target line, the club should never get behind that line, until the ball is struck. That is, you are swinging the club away well to the outside of the normal backswing plane, then wiping: from the outside in as you swing through the ball.

During the backswing, the forearms rotate the club a little more than normally, which opens the clubface even more.

In the downswing, along with the outside-in motion of the arms, the movement of the right hands and wrist through contact is that of a heavily sliced forehand in tennis - a stroke no good tennis player uses much, but it's correct for this shot. The hands rotate to make the clubface point towards the sky - to use another image, it's as if, with your right hand, you are holding a spoon and scooping ice cream with a long shallow action.