The torso should be bent up a little higher for the high side kick otherwise she will lose her balance right after the kick. Also, hips should be square to the chest, if her hips are turned in that means she's going to fall to the side as well. Don't forget guard up! Don't loosen or drop your guard for a kick especially a high side kick, fists in and closed, cover your chest! Looks good as art, looks bad in martial arts.

yeh this is very hard D:
I search youtube to find reference, but i can't made it good enough

That kick is a real kick, I can do exactly what she is doing, it's just a bad kick.

The next best thing from doing the techniques yourself is watching them in slow motion.
http://youtu.be/kjyvvqcTHh0

still thank you _A_~

I still have trouble with stuff like this. But the torso looks a bit off to me.