Piles. Or bags.
Seperate everything into a pile/bag. Have one spot for trash, one for things you want, one for things to put in storage, and one for things to give away.
Once you're down to the want pile, start seperating into smaller piles (one for books you want to put on your bookshelf, one for stuff to go in your closet)- that kinda stuff. Find out what category of stuff will be going in what part of your room (have a drawer for electronics, or jewelry, or whatever).
Works for me every time. Just don't get lazy at the end and stuff random crap somewhere. If you feel like you're gonna do that, take a mini break or put the pile aside for tomorrow. And I mean tomorrow. Don't procrastinate about it.
Once you do it- it cuts down on your future cleaning time. I completely cleaned my room about 2 years ago when I got it redone, and now even when I'm doing a "total" clean it only takes me about an hour or too. Just tidying up takes even less.
GOOD LUCK!