Ok, so here's my advice. And I have education in child development if that means anything lol. I would get a box, whatever size you feel is big enough. Gather all her stuff and put it in a big pile in the middle of the living room. Have her go through it all and put what she wants to keep in the box. The rest goes to charity. Have her go with you to give it to the charity. Preferably like children of mom's in a safe house, or foster kids, or disabled kids. Then she learns two things. You can't have everything you want and it is good to give to others. Then tell her that at the end of the day everything she wants to keep has to be in that box and in her room nice and neat. If it isn't, then you take it and put it in the "give away box" for those kids with nothing. If she wants something new, and her box is full, then she has to decide what in her box she is willing to donate in order to get the new toy or whatever. Never should she have anything more than what can fit in that box. If at night it is not in that box in her room, then it goes intop the give away box. Anything given away she has to come with you to donate. And you absolutely, positively cannot slide on this and let her get away with anythiong even once. Or else it won't work. I would also suggest a board with a list of things you want her to do daily to help out around the house and what not. If she does it that day she gets a star. After so many stars, however much you think is fair, she gets an agreed upon treat of some kind. Whatever she likes that is good for her. I hope this helps. If you try it, let me know how it works.