try Benjamin Moore Key Ivory West for the walls - it's a soft color and will brighten the space, but will work with other colors. Put a funky rug on the floor. Go to Marshalls or TJ Maxx or IKEA and get a comfy chair with a a small table next to it. If she has any artist friends at school, have her ask them to do an oil or watercolor of something she likes in a large canvas for over the bed (don't frame it). Replace those lights. Or, for over the bed, just print out a bunch of 5x7 photos of friends or whatever (black and white would make a statement) and arrange them in whatever frames you like. Going for neutral or soft colors will enable you to use accessories for color and change the look when it gets old.

We painted our girls room a light aqua color, it looks great with pink, yellow and blue. I always like a lighter wall and pop of color for kids rooms because I feel like they spend so much time in there playing you want them to have a happy space.

VERY creative, useful and sophisticated as well! I like the subtlety of the trunk color against the lighter wall. Have you considered designing these as a PT job???

The blue is awesome (grey is too trendy)! The reason it stands out to you is perhaps because it's the only real colour there. Bring in the blue in a window treatment, a small appliance that sits on the counter, a pretty tray or area rug. Also, it is more appealing often if there are more than 2 colours - so right now you have a white and blue colour scheme - bring in red or orange or fushia - something from the other side of the spectrum (like you did with the yellow flowers but in a more permanent way)!