1. See an ortho and make sure you don't have any current injuries (tendinitis, tears, sprains, etc. on any tendons and/or ligaments.
2. Stretch!!!! I'm 34 years old and I don't care what any current research says, I can tell you from experience that if I do NOT stretch before and after exercise (cardio and weights) I will have massive tendinitis flare ups (we're talking months in knee braces, medication, cortisone shots, etc)
3. Strengthen the surrounding muscles on your knee (quads, hamstrings, etc.)
4. Wear shoes supportive enough when you're practicing tumbling and/or jumps to help absorb the impact of the landings (this helps w/weak ankles too).
5. Physical therapy at home suggested by your ortho after you've been checked (he/she will still give you exercises to do even if you don't have any major injures..bc I'm willing to be you at least have enough inflammation on your knees to warrant it)
6. Topical prescription anti-inflammatorys like Voltaren (way better than popping motrin bc pills are absorbed systemically verses locally like topicals. You need a prescription for those though...they're not like IcyHot....)