What are the best colors to paint a girl's room specifically 12 and will love until she is 18?

At what stage should you paint a stripe...
Answers:    play around with the Sherwin Williams color visualizer to find something that you approaching. It is the best paint visualizer on the web, imho. I similar to how their color palette is laid out, I like that you can force out by color family & color entitle, the "painted" rooms look the most realistic, and it suggests coordinating color scheme. You can literally spend hours:
http://www.sherwin.com/visualizer/

How about "porcelain" (# 0053) beside wide vertical stripes surrounded by "silvermist" (# 7621)? That would look very pretty.
Where can i buy some nice cheap curtains...
Ask the girl. It depends entirely on her self-worth, but her tastes will move rapidly and repeatedly over her teen years, so near is no way to guarantee she will resembling it. Avoid extremes or fads.
I would suggest not pink. Usually blues, greens, or purples are fitting for bedrooms, because these colors tend to soother and refresh folks. Consider a lighter, milder palette, rather than hot, primary, eye-popping colors.