My paper, if you would even call it oganized, is sorted by color or theme. If it is a patterned paper then I try to put it in with what ever the predominant color is. If it came in a stack like a DCWV then I keep the stack together.
Pretty much the same here.
I keep stacks together until there is too little of it left.
I sort by theme first, so I have a spot for Christmas, Halloween, Disney (broken down further into Mickey, Pooh, Princess, general, other)birthday, nature (i.e grass, sand clouds), school, sports, other holidays, other themed paper (like popcorn paper, m&m,
lego etc). Anything that can't fit into a theme and isn't a part of a line I want to keep together (like DCWV stack, basic grey line etc) gets sorted by the predominant color. Except, I think I have a spot that is for bright multi-colored papers.
Last -- I have stopped buying paper just because I like it. Why? It is too hard to keep organized and once I put it away I forget I have it. So I very rarely buy indiviual sheets unless I have a specific project in mind that I plan to work on rather soon. The big exception to this is Halloween papers which I can't seem to resist, anything dinosaur for DS6, and DCVW stacks which I just like to buy.