"The best way to lower your score is to work on your game from a 100 yards in." - Wally Armstrong
One of the most difficult shots in golf is the short, high pitch shot over a bunker or water hazard. Most players struggle with this shot because it calls for a lot of finesse and timing with the club. It's hard enough to gauge the distance, but we also have to think about the height and flight of the ball, given the angle of the wedge.
The tendency during this type of shot is to try and scoop the ball with the clubface. We stand over the ball and see the steep face angle of the wedge, and we know we have to get it high, so we try to help the flight by hitting under the ball and trying to lift it into the air. This often creates a lot of wrist movement and mis-hits. It's a natural reaction on our part, but it kills the execution of the shot.
To create a proper pitch shot, we need to learn to hit through the ball and allow the club to do its work. In fact, the shot should actually feel as if we're trying to hit a low-flying shot with a steep-angled club.
A good practice drill for this shot is to take two sticks and some string and create a makeshift line about three feet above the ground in front of you. Then stand about six feet behind the line and try to hit balls underneath the rope with a wedge. Of course, you probably won't be able to do it. The angle of the wedge will send the ball over the rope each time. But by trying to keep it low, you'll be forced to hit through the ball, and you'll begin to feel the proper swing action for a good pitch shot. Once you get this feel, pick some spots out in the distance and practice hitting to them, using the proper stroke and motion. You should be able to feel the difference. And you'll find it's also easier to gauge the height and distance.
The single greatest thing you can do to lower your score is to increase your skills inside of a hundred yards. Work on your short game, and the rest will fall into place naturally.