I keep it simple when I teach 100-shooters the greenside bunker shot. The sand can be intimidating to higher-handicappers, but they have to overcome that fear. When you address the ball, stand with your body aligned slightly left of your target, and open the face of your sand wedge a little. Now make a normal swing. Your only thought should be to throw the sand that's under the ball out of the bunker. This simple idea gets you to accelerate through the ball and finish the swing.I know it's a short shot, but that acceleration and clubface rotation are so important. You can't throw the sand out if you hold the face open -- in fact, you just might dump it on yourself. To feel the correct action, try the right-arm-only drill above.
Chipping: Keep it simple -- for now
On chip shots, ball position and wrist hinge play a huge role in how high the ball flies and how much it spins. The farther forward in your stance you set the ball, the higher it will fly. The more you hinge your wrists, the more backspin you will create. But for someone trying to shoot in the 90s, I recommend playing the ball back in the stance (left) and using little wrist hinge -- almost like a putt. This will ensure ball-first contact, help prevent scooping and give you confidence. Only then should you try different ball positions and add wrist hinge (right).