For a finesse wedge shot out of high grass green side you must setup for a steep descending angle of attack into the ball. Put 80% of your weight on your lead foot…setup open or to the target and hinge your wrists up and outside the line on the takeaway. These are all steepening factors which you will need to come down on the ball and try to get as little interference as possible from a lot of grass between the club and ball at impact. The deep grass may well grab the hosel and try to shut the club face taking away loft which is bad. So set up for a vertical or upright backswing and thump down into the ball with a firm lead wrist. A little practice and you will be popping them right out of those bad lies.