This is a great before and after of a typical pre teen bedroom. There are two considerations with a pre teen room...coolness level, and clutter. Great ideas for cleaning up the clutter are crates, shelving, and hooks hanging in the closet. Use fabric panels to cover cluttered shelves, and baskets to hold perfumes, lotions and the like.
For coolness factor...bright colors, and geometric shapes usually rate well, without sending Mom and Dad to the moon. Note the simple painted and random shapes echoing the existing comforter...and how the bright colors evenly distibuted around the room make it work. My daughter loves this room!