1. Be familiar with the material. Don't come unprepared.
Know who and what you're auditioning for.
Research the show to make sure your music is cut right and in the style of the show.
2. Don't make excuses.
3. Make strong, clear choices.
If you're going to make a choice, make a bold one. Even if it isn't the choice they're looking for, they'll know that you're not afraid to commit to a choice
4. Don't come dressed in costume.
Seriously don't do it. Seriously. You will just make everyone uncomfortable.
5. Be nice to everyone you meet at auditions.
Not only because it's great to be a good person, but also because you never know who you're talking to. That person checking you in at auditions could be the assistant director. You never know.
6. Make sure your headshot looks like you.
If you don't wear red lipstick every day, don't wear it in your headshot. If you don't wear any makeup at all, don't wear it in your headshot.
7. Don't expect anything.
8. Relax. No casting director wants to see you do badly. They want to see you do well. They are rooting for you. If they can cast you, that makes their job so much easier!
9. Don't be glued to the script, but don't be afraid to read from it either. The director is looking to see how you play the role, and if that means you need to look at the script, that's okay! They'd rather see you do well, and make strong choices, while reading from the script than see you try and do your audition without a script and forget the lines because you're trying to be impressive.
10. Don't use the director or anyone in the audition room as the other character in yout scene. In other words: If you're doing a monologue or song, don't stare into their soul.