You'll probably need to know some cheerleading jumps. There are four main jumps in cheerleading - the toe touch, pike jump, herkie and front hurdler. You can search the web to see what they look like, but it’s important to learn them correctly. The judges will be looking at your form, not just how high you can jump. If possible, take a couple private lessons at a cheer gym, so you can learn the proper technique from an expert. There are also dozens of videos on Youtube showing how to do the various cheer jumps. To make them good, you have to practice, practice, practice!
You may be given a chance to show some tumbling skills, such as cartwheels, roundoffs or back handsprings. Don't be intimidated if you see other girls doing more difficult skills than you can. If a cartwheel or roundoff is the most difficult tumbling you can do, that's okay! Just do it your best and show it off! The judges would rather see you do a simpler skill that's done perfectly, than a more difficult skill that's done poorly or ends in a crash!
You’ll probably be taught a cheer to perform at tryouts, and you’ll be judged on how well you remember it, AND how sharp and tight your motions are. So practice as long and hard as you need to get it memorized! Practice in front of a mirror and watch to make sure you’re hitting each position precisely, with straight arms and quick, sharp motions.
You'll also be judged on your voice projection. Cheerleaders need to be loud - but not screechy. When you shout your cheer, yell from your diaphram and make your voice deep, sharp and clear. This sounds easy, but it takes some practice to get it right. And when you’re jumping around in a cheer and yelling at the same time, it’s easy to become breathless and lose your voice! So start “training” your voice by yelling a chant or cheer while you’re doing something active - jumping jacks, jogging in place, etc.
The number one tip people give for cheer tryouts is to SMILE! Sounds simple enough, but it’s easy to forget when you’re out there concentrating on your jumps or cheer. So start working on it now. Whenever you practice anything - jumps, cheers, etc - do it with a smile. That way it will become a habit, and you won’t have to concentrate on smiling when you’re out there in front of the judges.
Good luck!