One of the main things that you need to do before an audition is prepare 1 week-3 months in prior before the audition
Vocal Section-
When you are on stage in your audition make sure to always annunciate when you are doing your audition cut
If you have time before your turn always try to practice your song a couple times
Another thing that is really good to do before your audition is have a nice meal so your brain can process
And last but not least make sure to have fun!