Get fit if you aren't already. Cheerleading is a very intense work out.
Be flexible. Look up cheer stretches. You need a good toe-touch and herkie. Stretch every morning and every night. This will lengthen your muscles. You need good back, leg, and arm flexibility for stunts, jumps, and tumbling. The more flexible you are the less you'll hurt yourself, because your body will be used to bending and twisting.