When you have the ball, get into three point territory. Quickly tap the circle button. That should make you fake a shot, and your opponent should jump in the air. When he is at the top of his jump, shoot the ball. Your opponent won't have enough time to recover and will not be able to block your shot. This will give you a better chance of making the three pointer. (I've noticed that if a defender isn't jumping in front of you during a shot, the ball tends to have a better chance of going in, rather than him destracting your player.)