personally so please try it out first and don't see which one works for you
1. deep bunker soft sand (think marina bay). I'll go with something above 54 and open the club face AND stance. Ball forward and hit 1-2 cm behind ball the ball flight will follow the club face, the open body stance will make sure the club goes from inside to outside swing path (don't worry about this just do your normal swing it's automatically should be like that).
2. Deep bunker hard sand (after rain etc). I'll go with open stance still and hit clean on the ball.
3. Plucked ball / ball lie is crap. I'll go with normal stance and close club face on wedges.
4. shallow bunker. I'll just hit it as if it's a fairway wood swing / long iron. focus on maintaining stable lower body balance.
yeah.. i know lots of crap, but that's what I did.
My best technique is actually avoid getting into the bunker in the first place