How much time do I spend preparing?
The amount of time you prepare isn't as important as much as how you prepare. Each actor is unique in their level of experience with auditions. In addition, everyone must come up with a method and process that works for them. Ignore others who tell you how long they prepared. This is like when someone tells you how many hours they studied for a test. It's meaningless information. What is important is how you prepare and how you make yourself comfortable enough to go in and show the best of your talents.
What do I wear?
Comfortable clothing that works for dance and movement. Plain colors without words or logos or pictures. You want the directors to notice you and your talent and not waste time and energy trying to read what's on your shirt. No jewelry and minimal make up. Pull your hair back. Let them see your facial expressions and let yourself shine through.
What/How do I prepare?
Know the show. Watch movies, dvds, youtube clips, Tony Award numbers of the show and anything you can get your hands on. Pay attention to the time frame it's set in, the body language and facials of the leads and the ensemble. Someone in the ensemble may catch your eye. You don't just learn from leads and an audience doesn't just enjoy a lead actor's performance. Understand the theme of the show...is it dramatic, comedic, romantic?
Know the characters. Not just the leads but know them all. You may think you are suited for one character but the directors may see you in a different light. Be prepared to read for any role.
Prepare the readings. Out loud. With a partner. Watch your face. Read with inflection and facial expression. Add in gestures and some blocking.
Select your song with some research. Read what the audition notice calls for. Select something that suits your voice. Put in the effort to memorize your lyrics. Add in light blocking and facial expressions. Don't just think about what you will do in your audition. Actually do it. Practice it over and over until it becomes natural and that way you will look more natural.
Know yourself in your final preparation. Know what works best for you to calm yourself before an audition. Vocal warm ups in the shower or the car. A quiet moment reviewing what you've prepared in your mind. Close your eyes. Take a deep breath. Drink some water. Whatever makes you most polished. Be sure to harness your energy so you don't look like you are over the top or out of control.
Be prepared for curveballs. This sounds silly. How can you prepare for the unknown? The important thing is to have a little fun and loosen up. Sometimes a director will ask you to sing in a higher range or read a different role. Enjoy this. It's a good thing. Go with it.
Will there be callbacks and if so, what do I prepare for those?
Our casting philosophy has generally been not to use callbacks for all roles. There might be one or two roles we are undecided about. If we do conduct callbacks we will tell you what and how to prepare. It is difficult not to be too excited for a callback. Try to keep the hype within yourself to a minimum so you can focus on giving your best.