Audition in for sandy in Grease can you help?

Hey! I am 13 years old and I am auditioning for Sandy in a local 8-13 play of grease. I have a good voice and i have dirty blonde hair. Even my director who doesn't give out many compliments said i have a wonderful voice. I really want sandy! My audition is next Friday. I have a vocal coach and I am practicing my audition song Freddy My love with her. I cannot wear a costume. Any audition tips for getting sandy? thank you soo much!