This isn’t a shot many golfers practice, myself included, so it’s important you lower your expectations from this situation. You first goal is to make sure you get the ball out to give yourself a chance at a par and take double bogey out of the equation.
You obviously need to the get the club through the sand and under the ball but it’s more difficult from this lie. I would try and use the heel of the club a little more. It’s risky but seems to work better for me. More often than not the ball just pops out and you should have a putt to save your par at least.
Stand 2-3 inches further away from the ball than you would for a standard bunker shot. This lowers the handle, which helps the heel dig into the sand first.
The swing needs to feel much steeper than a normal bunker shot, a bit like you’re chopping down on a piece of wood.
Open the clubface and try and hit the sand about an inch behind the ball holding the clubface open through impact. With the heel coming into contact with the sand first, the club will naturally want to close down. A tighter grip pressure will help resist this.