Start with your sand wedge and a good lie, in other words some grass under the ball.
Only play this shot when you have to…ie: coming over a bunker or playing to a pin that is close to the front and you want to stop the ball quickly.
In a nutshell….You need to do the opposite of whats instinctive !!!
Break your wrist on the backswing, similar to the picture above and then hit down firmly to the bottom of the ball and continue through the shot keeping the left arm and club in a firm straight line.
The most common thing people tend to do wrong with this shot is trying to lift the ball over the bunker by scooping the ball into the air. Resist this temptation and try and hit down into the back of the ball. The action of hitting down will lift the ball.
Remember the club will lift the ball if you let it.
Allow your body to turn through with the shot, include your shoulders both back and through with this shot (the same for all shots).