What are some quick, good tips in acting and auditioning in a school play?

I'm 13 years old and I'm auditioning for the Genie role in my drama cl. We;re doing Aladdin Jr. and I really need some good tips. Everyone keeps saying oh practice, all you need is confidence. And I've been practicing a lot and I have full confidence. Is there anything that I can eat/drink, or breathing techniques? Please help me!!