The best advice for playing a shot with the ball above or below your feet is simply to play the hand you were dealt. I've gotten a lot of tips and heard a lot of talk about opening or closing the clubface or stance to try and offset the bad lie. This may hold water sometimes but I don't see a whole lot of sense in complicating things.
When the ball is above your feet, simply pick a target line that runs through the right hand side of the green. The ball will more than likely pull or draw to the left (if you're right handed).
When the ball is below your feet, (again if you're right handed), simply pick a target line that runs through the left hand side of this green, the ball will more than likely push or fade to the right.
This is all just playing the percentages, and maximizing your chance at putting for birdie. Practice these shots whenever you can, the more you get a feel for different lies, the more you'll know how far left or right to aim, and birdie opportunities will become more and more frequent!
