I'm not a parent or anything but I am studying to work with children and I have ADD so here's my opinion. First of all make sure that she knows the rules and expectations. Focus on rewarding her good behaviour, don't focus on punishing her misbehaviour. If she follows the instructions, note it and make sure that her coaches praise her for it. If she waits her turns, praise it again. Anything that is good behaviour make sure that she is praised and if she behaves (let's say 75% of the time) she EARNS her next lesson. Make sure that she understands this. After her lesson tell her what you didn't like about her behaviour but also tell her the good points and praise her for them. Then tell her if she earned her next lesson or not. If she doesn't behave she does not get the next lesson. It's better to reinforce positive behaviour than it is to punish negative behaviour. It usually gets better, quicker and more permanent results.
I would also add that maybe there could be certain rules that, if broken, automatically means she doesn't get her next lesson. By this I mean behaviour that is dangerous to her or others.
I would also add that maybe there could be certain rules that, if broken, automatically means she doesn't get her next lesson. By this I mean behaviour that is dangerous to her or others.