Keeping head still
 

I have been umpiring at lower levels for two years now. I've improved, but still feel like I move my head too much. Any advice? Thanks!

Watch the ball with your eyes, not your head. You can practice at home, get in your stance, put your hat and mask on and pretend you are watching pitches by moving your eyes. I changed to the GD system 3 or 4 years ago and I believe it helps stay rock solid on the pitch.

if you ever have a chance...have somebody video tape you working and grade yourself prior to watching the video..it's amazing how awesome that works...

Change your mindset and trust your stuff.
If that doesn't work, buy a mask you will trust.
As you implied, it's just [in] your head. :)
Good luck with it.