1. Don't start with accents
Starting with accented pieces and doing many accents isn't a good practice. GIVE good content, emote, smile, laugh, come alive, go dead!
2. PERFORM your piece
Don't worry about repeating a piece which has already been done.
A speech which has been repeated give you a chance to do better and give you a lead!
Focus on your piece and not the big names of the school or directors.
4. TAKE YOUR TIME
Auditions do have a time limit, but the evaluaters are looking for how well you can "settle" and " unsettle" yourself in the given time.
5. HAVE FUN
Just have fun and things would roll out like nature around you. Remember, acting is effortless!