Hi,
Welcome to this site, and thank you for asking a question here. I am sure you will get some answers that will help you.
Here is a link:
http://www.nancyredd.com/cheerleading/tips.html
It has some excellent tips on what to do, how to do it, what to expect in cheerleading tryouts. Also things you can do at home to practice.
I do wish you good luck, and hang in there.