I think it’s in a young person's nature to have a messy, cluttered room. When it comes to selling your home, this can be problematic, and it's where staging a kid's room to sell comes into play. Potential buyers don't want to see personal effects strewn about or dirty laundry on the floor--this much is obvious. Yet, something that you might not consider, is that they also don't want to see centerfolds of the latest "it" guy or girl in the teen world, wall decals, or extra decor motif that can be taken down while showing the home.
This client's daughter had a typical room for a young girl, but we needed to make it a little more generic and organized before buyers came in. I recommended that the client take down all of the posters and also remove the wall decals. Even something as simple as taking a CD player off of the floor and setting it on the dresser made a huge difference. We diminished some of the clutter, and removed the curtains, which broke the room up (even though they were sheers, they kept some of the light out and hid the window). Adding natural light to a room almost always makes it appear larger than it is.
The basics with a staging a kid’s room, are to make sure there is no clutter, the bed is made, the windows are not obscured, and that anything “extra” décor-wise isn’t left out. If it can be taken down temporarily, please do so.