Ball below your feet
How successfully you play this shot is based on set up and balance. On any uneven lie gravity is trying to throw you off balance. Because of this precarious feeling I recommend you select one more club than you would use off a flat lie. This will allow you to swing in balance and the longer club will discourage hitting the ball thin.
The set up.
Try placing the ball in the center of your stance. Grip the club at the end of the grip to make the club as long as possible. Since this shot usually fades, aim more to the left (right handed golfer). Sit back into the hill with the weight favoring the middle of the feet to slightly on the heels.
The swing.
Always take a practice swing on an uneven lie to determine your balance and where the club is making contact with the ground. Retain constant knee flex throughout the shot to maintain control and balance. Take one more club and swing smooth. Remember to finish the shot in balance.