Honestly, the best way to figure out how to best arrange your room is to move everything again and again until your satisfied with it. It sounds like a lot of work but will be totally work it once you find what works best for you.

I have a closet, one window, book shelf, dresser, hanging mirror, vanity, and a bed with shelves for a headboard. My room is really small and I need a new way to decorate and rearrange it.