The first idea that you may want to incorporate are funky accessories. There are many such as cute pillows, jewelry displays, decorative lamps, unique art pieces, and unique rugs.
The bedroom closet is often a focal point when it comes to the bedrooms of pre-teen girls and teenage girls. All too often, the closet space becomes cluttered because it makes a nice area to store things.
Bedroom paint colors are another area in which teenagers typically have a lot to say when it comes to their personal living space.