Accompany your teen to a bed and bath store, and have him choose the bed set that most appeals to his style. A comforter, sheets, pillowcases, bed skirt and toss pillows can give a completely new feel to the room.
Paint the bedroom a color that complements the new comforter. If your teen wants a very bright or very dark color, paint just one wall to act as a focal point. The wall at the head of the bed would be the best choice. Keeping the other walls light will help make the room seem bigger.
Replace any furniture or accessories that are too childish with new items that reflect your teen's age and new sensibilities. Toy boxes and Teddy bears will make way for computers and iPod docks.
Cover the floor with a new rug that picks up on a color in the bed comforter. Lighter colors will give a bigger feel to the room.
Provide desk space where your teen can work on a computer and study. A desk lamp in a bright color can add a touch of cheer to the work area.
Allow for lounging with a comfortable seat or bean bag chair where your teen can enjoy listening to music or chatting with friends.
Hang artwork or photos chosen by your teen on the walls. Whether it's Twilight or Halo 3, posters and artwork make a room your teen's own space.
Install a closet organizer, with shelves and cubbies for holding clothes, sports equipment and other belongings that need to be stored.
Place a mirror on the back of the bedroom door, or on the closet door. Your teen can make sure he's looking good before stepping out for the day, and a mirror will make the room appear larger.
Place a bookcase or hang shelves to give your teen a spot to display treasured belongings and collections. Whether it's a collection of favorite manga characters or trophies won at karate, your teen will appreciate the chance to show their style.