First thing we have to understand about bunker play is that there are 2 VERY different scenarios.
Fairway bunker play & Greenside Bunker play vary greatly in required technique/mechanics.
Fairway Bunkers play very similar to a standard full swing out of a tight fairway/lie. I recommend a normal setup, backswing & finish with the same club we use at that distance (unless the lip/wall in front of you is too much for that club to clear, whereas we might have to use a higher lofted club just to clear that obstruction). Though “picking” the ball is commonly discussed, we don’t ever want to top it into the wall, hence leaving the ball in the trap. We want to hit the ball first, no differently than fairway play, contacting some sand forward of the ball.
Greenside Bunkers, however, require a more customized shot more often than not. Being that the wall of the sand trap will typically be more impressive in these Greenside Bunkers, we need immediate height, which is only produced when using larger type swings. Therefore, we must employ our highest lofted clubs (~SW 56 ~LW 60). We need to have a large (relatively full) backswing & follow through to achieve the height, but commonly we don’t want to exceed 15-20 yards. By aiming approximately 2 inches behind the ball, we can impede our distance quickly and easily. Opening the club face heavily is extremely important in fluffier sand, but in firmer and/or wet sand is not at all necessary. Understanding the grade of sand is essential to knowing how much the face has to be open.
These shots both function on full swing mechanics, so if you can hit nice high irons from the fairways and light rough, you can hit these too! Simply understanding your scenario is arguably the most challenging aspect. PRACTICE!