For low shots, it's tough, but they are easier to do if you run on to a lay off and strike it first time, more often than not they will strike it perfectly into the ground or they will blast it over, just gotta hope your shot stays down. As for the dummy, i suppose you mean the feint shot? Just press shoot then straight after press pass and they should touch it to the side without shooting. A straight forward dummy is just to tap the sprint button when a pass is coming to you and the player will step over the ball and let it go through his legs.