Correcting "Fat or Thin" contact on short approach shots

Believe it or not the most important impact factor in short approach shots is the clubhead's angle of approach into the ball. Weekend players struggle with this shot not because of mis-direction, but rather due to the clubhead reaching the bottom of the arc before contacting the ball. If the clubhead catches in the turf and loses its forward momentum it results in a "fat" shot. It the clubhead skims or bounces off the turf it then hits the middle or upper part of the ball resulting in a "thin" shot. In either case it is the clubhead's level or upward movement rather than downward angle of approach causing the poor contact.
First, choose a more lofted club than you think you need for the required trajectory. Then work on a proper set up so that you contact the ball with a downward moving clubhead. Move the ball far enough back in your stance (to the right) and your hands far enough forward (to the left) so that you catch the ball during the downswing. Here is a drill I often recommend. Place a golf ball about 10 - 12 inches behind your ball and practice hitting shots without touching the second ball either on the backstroke on downstroke.
With practice you'll soon be making solid contact with the ball and shooting lower scores as a result.