I want to be a cheerleader as well and taking dance, gymnastics or tumbling classes will help.
Tumbling
Flexible
Strong
Jumps
Stunts
Motions
are things you need to know and be as a cheerleader
Tumbling- Tumbling is what I suck at. You need to be strong and flexible to do the tumbles. The first thing you need to be able to do is a handstand then a forward roll then a backward roll then a cartwheel. If you can do all these things your in luck. Then we go to the walkovers. The front walkover is quite easy and the back is easy once you can do it. There are other tumbles but these are the easiest and you have to be able to do them first.
http://ezinearticles.com/?Cheerleading-Tumbling&id=750922
Flexible and Strong- To be more flexible stretch. To be stronger go to the gym and lift weights.
http://cheerleading.about.com/od/flexibility/Cheerleading_Flexibility_and_Stretching.htm
http://ezinearticles.com/?Cheerleading-Fitness-and-Strength-Training&id=4828913
Jumps- For jumps you have to have strong leg muscles so you can jump really high. Jumps also require flexibility like for a common jump the toe touch.
http://www.monkeysee.com/play/13596-cheerleader-strength-exercises
Stunts- Depends if your a flyer, base or spotter. If your a flyer you do the tricks. If your a base you hold them. If your a spotter you help the flyer up to do the tricks. To be a flyer you usally have to be small and light. To be a base you have to be stong and to be a spotter you also have to be strong.
http://www.cheercoachonline.com/cheerleading-stunts.html
Motions- Motions are just simple moves you have during the performance. There really easy.
http://nca.varsity.com/pdfs/Motions.pdf
Good luck with your tryouts next year