Don't arrive late, make a lot of noise, or generally be rude on movie auditions. It doesn't fly well if you disrespect their craft, even if you don't mean to. If you aren't cast for movie auditions, there are many reasons. You may not have fit the right type, or you simply were not what they are looking for. Move on to the other movie auditions.
Do anything to take your mind off of the fact that you are in consideration for movie auditions. It will prevent you from going crazy with anxiousness before the cast list is posted, and prevent you from being horribly depressed and disappointed if you don't get cast. You cannot decide that you don't want a role won through movie auditions at the last minute. If you've been cast, you've made a commitment (unless it's for a major role and you specifically asked for a smaller one because you couldn't put in the time a major role needs) and that commitment means that you don't say no to that role unless you have a very good reason.
Please be aware that the world of movie auditions is extremely competitive. People may not follow the above rules and still get cast through movie auditions, they may be completely rude and still be liked by the director, etc. There are a number of variables that you simply cannot control when you are auditioning, and there are no real specific unions to enforce rules of fairness. And if you thought life was unfair, everything is about ten times worse when you decide to be an actor. Be aware that you're in for disappointment, as well as frustration. Take it all in stride. That's acting, and it's what we love.