We have these stands that you put your foot in and it'll help you balance, or get on a chair or something but make sure if you fall you wont hurt yourself! While you're in the air, spread your toes apart it helps too in my opinion :) Also, pretend theres a string at the top of your head pulling you up, so make sure you're pulling your shoulders up, squeezing your whole body! A main problem i usually have is my hip going out so try staying over your stunt. :)
I started for my high school team last year, being the smallest and lightest on my team and this year i made varsity being the point flyer and never knowing how to fly or what to do a year before. Also if you're going to be a flyer make sure you stretch everyday! (:
If you could get a stunt stand they work amazing but there really expensive. So try doing your stunt positions on a step or on a small stool. Also when your flying try to shift all your weight to your supporting leg and get balanced before moving the other leg. And remember to be tight!
Practice standing on one foot or if u have your scorpion or needle then u can see how long u can hold it for. That's how I learner how to keep my balance. U can always buy the thing that helps practice being a flyer at home. I forget what its called but u can look it up. Hope this helped :)
practice on a chair. make sure it is flat. put only about half of your foot maybe a little more on the chair. keep doing libs, or whatever you are doing in the air over and over again until you get it.