The auditions I’m involved with start this weekend, so let me add one last random note on vocal auditions. I personally don't care if the song is memorized. I've heard lots of people apologize for not knowing the words, but I figure it isn't a memory test, it's a singing test. I have no doubt about your ability to ultimately memorize a song. However, your best opportunity to give a good overall impression may be just during the time you are singing. So, if you can really perform it, all the better. You don't have to put in pyrotechnics and backup dancers, but your personality and star quality will probably come through more easily if your eyes aren't glued to the page. If you can shine while glancing at your notes occasionally, that doesn't bother me a bit. Of course, I can only speak for myself.
If you happen to be sick, go ahead and mention it, but I find it often ends up sounding like an excuse, so try to not make a big deal of it. I've heard too many claim illness as though they'd be Tony Award winners if only the pollen count wasn't so high. I've heard people sing just fine while sick, even if not at their best. I can tell if someone's congested or if their throat is sore. Their voice may not be as well supported or strong, and range may drop. But sickness does not destroy sense of timing or pitch or confidence, so most directors will be able to look past your sniffles and scratchiness. If you really think you need a healthy opportunity to show 'em what you've got, ask. Likely, they've been able to determine what they need, and will let you know if they want a second look.
Remember that the very worst thing that can happen is that they'll pick someone else. That's not really that terrible, is it? I’ve never seen anyone injured or attacked at an audition yet. They won't post a video of your audition to Youtube. They won't tell all the directors in town not to cast you. They won't prevent you from auditioning again in the future. Try not to let your nerves get the best of you, take a breath, and try to learn something from the process!
Final advice – be confident. If you aren’t, use your acting! Pretend! Ask questions if you need to. They want you to do your best, really. They will be nice. They’ll smile when you sing (the nice ones, anyway - the ones you’d want to work with). They’ll say thank you when you’re done. Let your personality come out. They know you’re nervous, but they’re looking for potential. Be memorable, be interesting.
Razzle dazzle ‘em!