Know where you are going
When I was starting out in college, I majored in theater (emphasis on technical theater). Silly thing is, I only received an Associate of Arts (2 year degree program) in theater, because I wanted to be an archaeologist. So, yeah, I went to another college/university to get my degree in that. But I digress. While getting my degree in theater I had to take acting classes. Acting can be fun, but I prefer to be behind the scenes. Something very useful that they teach the actors is to know where you are going. This is useful for them when something goes wrong (someone forgets a line, there is some technical glitch, whatever). It is obvious when you have an amateur actor on stage when something goes wrong because they will often freeze, run off stage, or do something really stupid. On the other hand, a well trained actor will handle the situation so well that you, in the audience, will be hard pressed to know if they are covering up a faux pas or if they actually rehearsed it that