It's kind of easy to over-complicate bunker shots. My bro threw me for months by telling me he hits his sand shots harder than he hits his driver. I now think this is absolute nonsense. Brothers, eh..?
Swing really easy. I like to think about a nice little stop at the end of the back swing that doesn't need to be thta far back - waist high? Whatever...
The most important thing is GET THE CLUB THROUGH THE SAND. Really concentrate on the follow-through, and the further you want the ball to go, the more follow-through you want. Visualise it as trying to throw the 2 inches of sand all round the ball on to the green.