Acting auditions can broken down into roughly three sections, The Preparation, The Performance and The Result. We'll look at all three which will give you enough ideas to make you a little more relaxed about the whole process.

THE PREPARATION

Preparation, as any job interview book will tell you, is essential.
Firstly, do as much research as you can, be it the character you going to play, the director, the company or even the writer. It will show thoroughness and dedication that could be the deciding factor in your favor.
Secondly, make sure you know your monologues, you should have practiced them out loud in front of a variety of people to get as any opinions as possible, if you can't get a wide range of opinions you may find it useful to record yourself(video or audio), this gives you the chance to evaluate your own performance from a slightly different perspective.
Thirdly, know exactly where the location of the interview is, how long it takes to get there and arrive early. This allows you to relax and find some where to warm up.
You could be hanging around for a long time so take a book, some water and food or something like an ipod to keep you relaxed and occupied.
When in the audition environment it pays dividends to be nice to everyone, remember, todays rival actor could be tomorrows hot new director. This Don't be intimidated by the other actors auditioning with you, they will be just as nervous as you are. even if they appear cocky that doesn't make them a better actor than you!

THE PERFORMANCE

First impressions count, so upon entering the acting audition room be confident, positive and friendly. It may be helpful to remind yourself that these people in front of you are on your side, they actually want you to be great! Its good to be as open and personable as possible because you want the director to want to work with you personally as well as professionally and any advantage is an advantage.
Try to keep any questions you may have to a minimum, these are busy people and too many questions can seem overly ingratiating.
Your initial monologue should not really be more than two minutes long, have others prepared, these should show your range and diversity, and also have a longer monologue prepared, just in case the Director requests it.
The director may ask you to reread after direction, so good listening skills are important, at this point its better to ask questions than to assume that you know what the director wants, accepting direction also requires flexibility, so don't stick too tightly to the same old way you've done the reading in the past.

THE RESULT

No article on acting audition tips would be complete without a word or two about rejection.
As you have read there are many ways that you can improve your chances of getting a role, but most actors will get turned down for most jobs most of the time. You could do all of the above and more and still be overlooked, but you should not take this as a comment on your ability. It just indicates that the casting panel thought that someone else was more suitable to that particular role at that particular time.
If you do get called back for a second audition then well done. The same basic rules apply with a few subtle tweaks that will have to wait for another article.

Thanks for taking the time to read my acting audition tips and I hope it gave you a few things to think about.