I like to take an analytical approach to organizing: sit down, write out the most efficient procedure to go through everything, and set up a sorting station. That usually involves coming up with categories of keep, trash, donate, and "belongs in x room". For example, if there are things in the dining room that belong in the kitchen, there will be a box labelled "kitchen" which later gets taken to the kitchen to be put away or sorted.
From experience, a "maybe" pile can be very helpful. Technically it doesn't seem like the most efficient thing to have, since one will end up looking at some of the same items more than once. However, it may speed up the decision making process. Anything where I have to pause to think about it, I just put it in the maybe pile instead of staring at it and creating a bottle neck. Then, once I've gone through everything else, I can go back to the maybe pile. Since I've seen everything else in the room, I have a better feel at this point for what I really need to hang onto. I have also had time to think about the item on a subconscious level, so that tends to gradually decrease my attachment to it.
As an example, I once went through about 500 books. They wouldn't fit on my shelves any more, not even double stacked. Many of the books were easy to make a decision about. However, there was a stack of over 100 books in the maybe pile. They were books I hadn't read yet and kept putting off, yet I kept telling myself I'd get around to it eventually. Or they were books I had read once that were mediocre, but I wasn't entirely convinced I wouldn't want to read it again someday. I let that pile sit overnight. In the morning, I didn't have to look again at any of them, I just immediately got rid of the whole pile. The logic was that it didn't make sense to keep a book I wasn't looking forward to reading, and it was so much easier to come to terms with that once rather than to go through it 100 times over.
I stumbled on another mental trick when I was trying to tidy up my room. I had formulated a plan for where everything would go and the most efficient order to complete tasks. And yet... I just couldn't seem to get into the process of cleaning my room. I knew exactly where the logical place to start was, but it was like pulling teeth trying to get myself to do it. The breakthrough came when I moved my music stand out of the main path. All of a sudden, it felt like I could move around easier. I cleared everything out of the path, then began dividing items up into general categories (books, clothes, cds, papers, etc.) and piled them up in various corners of the room. As soon as I did that, I was able to proceed easily with my original plan of action. I suspect the reason I kept getting stuck was because the clutter in my room was visually overwhelming, and clearing a space made it more manageable. Not to mention easier to walk.