(1) Keep the clubhead outside of your hands. If it ever moves inside them, that is, closer to your body, you won't make the steep swing necessary to blast the ball out.
(2) Point the clubface at the sky in your followthrough. If the face points left, then it's closed, and you probably took too much sand and left the ball in the bunker.
(3) Focus on the flange (the rear portion of the sole of your club). Try to hit the sand with that instead of the leading edge. It's the proper way to take sand out of the bunker and use it carry the ball up and out.
Hit the sand with the sole of your club, not the lead edge.