Need Some Help

[Adam]

The trick is to learn to watch the whole defensive player and still focus on a specific part. Example: When a shooter is going up, especially on the perimeter, you need to watch for the hand on the arm (so you are kind of watching the ball here) and then fade out to catch their bodies on the box out.
If the ball handler is moving, you need to be even more aware of the defender's position for a block/charge. There's a lot to watch for, and it really comes with experience. Watch as much basketball as you can when you're not reffing, and try to watch for tendencies on certain plays.