A parent of my student asked what her daughter can do to start preparing for an A Capella group audition. Below, inspired by my reply , is a three step plan for improving your audition skills. It's not easy and it's not quick, but the most effective things rarely are.
Learning to audition is a tricky process, as it is mostly an experiential thing, You can learn all the technique in the world and practice every day, but when you are in the moment there is the element of stage fright which is so difficult to overcome.
As a professional musician and coach who has trained hundreds of musicians and performed in hundreds of concerts, I still feel that nervousness and anxiety each time in front of an audience. In my experience, and in the experience of the countless professional musicians, actors, dancers, speakers, and other performers I've asked, it's not that the feeling goes away as you progress. What happens is we learn to take that feeling and reinterpret it as excitement, passion, or some other positive emotion. Intellectually, I know that the buzzy feeling I get on stage today is the same one that had me shaking before auditions in high school. Emotionally, it feels like excitement and anticipation, and it tells me I'm ready to go out and give it my all.
"That's all well and good, but what can I do to get there?"
The first step is to do the audition NOW, don't wait til next year or the next show, just giving it a shot and saying "I won't get in, I won't get the lead, but I'm doing this to get better at auditioning". Honestly, the only thing that makes you better at auditioning is doing it more often. I am pretty good at interviews and auditions now because I've done hundreds of them, and I'll still do them even when I don't want the part. In fact I regularly interview and audition for new choir positions even when I know I don't have the time for them, just for the experience. When I actually need a position, I bring not only my skill and experience to the table, but the dozens of interviews I've done as well.
Beyond that, daily singing will help to build skill more than anything. Consistent technique work will do so much to improve a singer. You can download a free CD of vocal warmups and exercises from my website. What you can improve which will very much impress judges is ear training - the ability to sing in tune, pick up a part quickly, and read music. This comes first from a large amount of listening and singing.
After the listening/singing foundation has been laid, musicians need a systematic way to approach deciphering the language of music. I've written on this before, and will again in the future, for now you must know that the scientific literature states that all systems of ear training (fixed/movable solfege, numbers, letter names, intervals) work about equally well, the differentiator is the instructor's mastery of the method and teaching ability, the amount of time students devote to practice, and the outside work of the students. Pick a system and stick with it, get a coach, or buy an audio/book program.
In the broader scheme, stage fright is stage fright, and working on it in any context will help to improve in auditions. So public speaking, running for office in a club, reading a passage at church,auditioning for anything and everything that comes up, performing in front of family and friends, trying out for a sports team, doing announcements over the intercom, giving a speech in class, etc.
Getting over the fear of being judged by others and feeling totally comfortable standing up and showing your stuff in a relaxed way is incredibly difficult and takes a lifetime to master, best bet is to get started now and just practice it in the real world whenever you have the opportunity.
Action Step: Google auditions in your area for your artform, pick 3 that fit in your schedule (even if they are way out of your league or genre) and put them in the calendar today. Good luck, though if you audition enough, you won't need it.