Take a straw!
Singers! Take a straw, a typical 9" straw often found in delis and fast food chains, and sing your audition song(s) into it, sing it once very choppy and staccato, and then overly smooth and legato. Do 5 minutes of a warm up using the straw, this will be a great pre-audition exercise to get you ready. Also, focus a bit on the breath control, making sure the connection is around 2inches below your navel. The exercise and sound is quiet for those around you, but so beneficial and complete for the instrument minutes before you go in to the audition room. Enjoy!