Usually you want to splash your ball and the sand out of a bunker, but when the ball is buried this will cause a skull, so in this situation you need to use your sand wedge to dig below the ball
For downhill lies reposition your club and body so that your stance is parallel to the slope your ball is on
When the ball is on an uphill or above your feet lie all you have to do is make some adjustments to your set up and stance