SFGate

eztia Are you planning to paint one wall the darker blue and another wall the lighter blue?
Will you be getting new bedding? It seems to be going "backwards" to buy the bedding before the paint, but I have learned from reading thousands of these discussions that it really is the best way. Take an enlarged photo of the girl's hair when you shop for bedding.
What kind of "feeling" do you want when you are in the room? Serene, creative, energetic...? These words can help you decide on other decor for the space.
Your furniture looks like it is very good quality, so nothing needs to change with that.

You might want to start your own Ideabook on Houzz. Go to PHOTOS. Scroll down to Bedrooms. In the search box, be sure to include the word "blue," for example, "tween girl blue" or "teen girl blue".

Ruth Ann Chaplik-Secreto I think you should really go farther & do one wall blue & one wall with a bunch of " strands " of flowing blue .. Or draw your eye & hair on a huge sheet & make a canvas of yourself . Rainbow rug ? Throw pillows in yr fave colors ... Go wild you are young !! Take a lamp from a resale shop & spray paint a bright color & some picture frames.. Have fun !

Gail Elwyn Nice room to start with. The furniture looks like quality pieces like stated above. Consider striped blues with some white stripes as well to break it up. I would hang one large piece of artwork on the wall over the bed or put two or more evenly framed pieces to frame out the bed. I would move the bed closer to the nightstand and put in a coordinating rug. Also buying the bedding and rug first to pull in those colors on the wall (like stated above as well) is a good way to start. You could do a white comforter with decorative pillows and a throw to not make the room too heavy.

Welcome Home designs I definitely agree with Ruth - make your room unique so it reflects your personality.
I've attached a fun photo for inspiration.
Go for it!