Setting yourself in the bunker should be a comfortable and easy experience that is somewhat close to your driver set-up.
Many people adopt a stance that replicates no other shot in golf and the result is a swing that has been manipulated to meet the needs of the incorrect set-up position.
With the driver, your stance is wide, your ball is positioned around the left heel area, and your spine is tilted away from the ball. These are classic positions for ball flight elevation.
Apply them in the sand and add one more bunker-specific move - nudge your hips forward a little towards the target, allowing 80% of your weight to rest on your target side and keep it there for the entire stroke (no transfer of weight).
The nudge and omitting weight transfer will promote the low point of your clubhead arc to be past the ball ensuring that the strike is on a downward path. Remember: to get the ball to go upwards, you need to swing downwards!
Don't assist the ball into the air
With my low point set past the ball (target side) thanks to my nudge forward of the hips, you can see in this image (above) that my sand explosion starts inside my left foot through to outside my left foot, with the lowest point of the divot being in line with my left foot.
I have made no attempt to assist the ball into the air. I have applied a perfect set-up position, so no manipulation is required throughout the stroke.
One important thing to mention here is the nudge is a nudge or slide of the hips, NOT a blatant shift of weight.
Putting more weight on the left foot without the nudge will encourage too steep a swing and reduce your chances of a consistent low point and produce a hindered follow-through.