Throughout my time auditioning, I've collected some knowledge on the whole process and how to become successful at it. Here are my tips for mastering the audition process.
Before the Audition
Read the Breakdown
Twice. Thrice. Be thorough while reading. Are you right for this project? What are they looking for? Make sure that you follow directions. Did they ask for 16 bars? What about a monologue?
Do Your Research
Who will be in the room? Who's casting? Who's the director and choreographer? What about the composer of the project? Look at what else these people have done. It will inform what material you choose to audition with.
Prepare Your Material
Select fitting material to the project. Once again, make sure you're following directions. A 16-bar cut and a 32-bar cut are very different. Once you have selected your material, work on it a little bit. Make it the best it can be.
In the Room(s)
This is where you check in with the monitor or put your name on a list. It's fairly self explanatory and once you do it once, you get the hang of it. That being said, don't be afraid to ask those around you if you need help. Someone is bound to know the answers to your questions.
The time spent in a waiting room can add to your audition or take away from it. I like to go over my material in my head once or twice, then do something else entirely. Like read a book, or play a game on my phone. This time is different for everyone. Everyone has a different way of getting "in the zone". Find what works for you. It's important to find a way to keep your nerves down if at all possible. Auditioning as much as you can to flex that muscle will take some of the nerves away.
In the Room
My main tip for when you're actually in the room is to be a human. Say hi to the folks behind the table, a quick "hey, how are you guys" will work. If you're singing, go over to the pianist and go through your cut with them. Then comes time to actually audition. I can't really help you as much here because it's so specific to each person. What I will say is to let yourself shine through whatever character you're portraying. You have your unique perspective, and nothing is more enthralling than seeing human behavior in a performance context. After you're done, collect your book, etc. Thank the pianist or the reader(ALWAYS) and head out of the room. A general thank you to the folks behind the table is customary.
After the Audition
Take out your audition journal and fill it out. This is a time for reflection. What worked this time around? What didn't? How can you improve the process next time? These are all good questions to ask.
Get Rid of It.
Lastly, rid the audition from your mind. Go do something with your friends. Go shopping. Call your mom. The worst thing you can do is obsess over the audition you just had. It will drive you crazy. I like to go on long walks and listen to (non musical theatre) music.
These are just my tips for success in the audition room. Everyone will tell you something different, so I advise you take everyone's opinion with a grain of salt(including my own). As always, my inbox is open for any inquiries you might have.