I need help figuring out ways to cheaply and easily organize my bedroom as well as my desk area. Mostly my shelving storage units become cluttered. My desk is my space to have random school supplies (I'm heading into grade 12) and clothes as well as my alarm clock.

My room isn't very big and has many pieces of furniture in it. A large unit with four long wide drawers and two equally as big shelves. On either side of my twin bed I have ikea tall units that have 5 shelves in each. Then high up over my bed connecting the two units is a long unit with four small shelves (2 on each side). In addition I have a desk and a couple other units, one with my tv on top.

My big question is how do I decide what shelf to put what. I have two shelves for some of my books. One for movies and all the rest are cluttered with things that don't go together. Any help is appreciated.