I would say going light grey on the walls is OK, but don't go black...just bring black in using accents like picture frames, a throw rug, trash can etc. I would also add in some silver for accent. Maybe get a red bean bag chair! On your window I would look at a woven wood blind.i think dont worry about the color and stuff just put a whole bunch of crap in the room that you think you might want or need and as youre in your room for a couple weeks or months just start shifting around what you think needs to be shifted and if you want something else put in then just put it in
