I'd say use your favorite color as a main theme throughout the room and then choose a complimentary color to accent it! Otherwise I always go for calming colors if I can have my choice.

I'd say lots of shelves. You can never have too much organization >:3
/looks around at her disaster of a room.

Yup. Definitely get lots of shelving/storage! Right now a lot of places have bright fun colors for back-to-school!