Have your dance teacher help make you improvements. What I don't recommend is have someone like you mom help you because my mom always sugar-coated things. Also always make sure your wearing what ever type of shoe that your going to be wearing on stage like ballet shoes, foot undies, etc.
Pick a spot on a wall and look at it when you turn. Keep looking at it while you're turning. Then, at the last moment of your turn, whip your head around and look at the spot on the wall. Kinda confusing but it helps!! :)