Something else you can try if your not doing it already is have him use more rudder on approach. A guy at my field told me to start doing this and it really improved my approaches. When you turn onto final use the rudder to maintain centerline, and use the ailerons just to keep the wings level. Start practicing this up high using only the rudder to turn. Another thing to watch out for is overuse of the elevator. Try to maintain a constant rate of decent. Because of fear, the tendency is to keep pulling up while decending, and then the plane ballons up. Again, just takes practice.