[FMadera]

Are you following the flight of the ball, or are you getting ahead to the setter's hands? If you're following the flight of the ball, I'd urge you to learn to recognize the trajectory and speed of the ball off of each contact to get ahead to where the ball will be. When you get ahead to that next point of contact, your relaxed eyes will make things much easier for you to see.

You probably should also watch a match with experienced officials to see what they call. You might learn how certain violations look. In addition, you might want to videotape a match you work and have someone watch it to show you specifically which balls should have been called (or not). There are good officials camps out there where you can have your matches recorded and clips given to you for educational purposes.