Being well-prepared is the best thing that you can do. This can mean applying rehearsal techniques to the point you can feel confident in your knowledge of the routine. Mental preparedness is the most important. It's good to be physically able to do the routine, but you don't want to wear yourself out. Many dancers rely on mental review strategies before an audition. Making up a sentence that helps you remember the order of the routine is effective for some, while others prefer to visualize themselves performing an excellent run-through before falling asleep the night before. Each performer knows what works best for them, so do what makes you feel secure.
First impressions are often the most important. You want to look good in front of the judges, because they only see you for a limited amount of time. Keep your hair back from your face, slicked into a pony tail, with special attention toward obnoxious fly-aways. Wear a limited amount of makeup to highlight your best features--mascara and a natural lipstick at least. Wear form-fitting clothing that doesn't expose too much skin. Wearing a colorful top may add to your memorability--the judges will remember you as "the girl in the orange top." If you can, stand in the front of the group, so that you are the first thing the judges see. Smile, look pleasant and be confident.
It's ideal that you know every detail about the routine. But if you do make a mistake, be confident. Don't get discouraged. Smile and continue as if nothing happened. The judges can't see everything, and it's possible they will overlook or forget your error if you are confident. If you make your mistake obvious by becoming visibly discouraged in your body language, it's also more likely you will make another error.