10. Always support your stage manager (rather than critiquing them).
I recently worked on a show where I was on stage calling the show (my director called it "reverse in-the-round," audience in the middle, action on the outside) and there were several places on stage where the actors and audience could hear me whispering my cues. One incredibly egotistical actor came up to me one night and said that my cue-calling was distracting him from acting. I was upset because 1) what? Really? and 2) he had no lines and his face was covered with goggles and a respirator. Anyway, one of the actresses spoke up and defended me before I could even open my mouth. Her words of support made me relax a little and made me feel glad that she understood how hard I was working.
Also, I had lines in this show. It was a werid, but very cool experience.