Uphill and downhill lies add to the difficulty of bunker shots.  Here are some suggestions that will help you negotiate these lies.

Uphill:
Address the ball with it forward in your stance and your shoulders tilted more than normal in order to hit through the ball without too much digging but taking just the right amount of sand.

Downhill:
This is the most difficult shot out of the bunker.  At address have your hands ahead of the ball to create more of a descending blow.  You must swing down and through with authority in order to get the ball lofted.