You have probably heard all these already but my top ones are:
1. Strong whistle! Strong whistle! When giving that
strong whistle get your arm up, open fist or closed depending on the situation. (Did I say strong whistle?)
2. Slow down! After giving your strong whistle give a count of 3 before lowering your arm. If a foul go to
a spot on the floor to report. Go to that same spot every
time. Get in the habit of pointing ball direction and
where the ball will get put in play for all fouls &
violations.
3. Don't call what you can't explain! If it looks ugly or
you're not so sure of the rule let it go. You don't have
to prove to anyone that you know the rules, they already
know that you don't and they'll tell you so whether you're
right or wrong!
4. Hardest part: trust your partner! Don't look at the
ball if it's out of your primary. Learn how to track the
ball using your peripheral vision and by the activity of
the players.
Finally have fun & let us know how it goes.