Whenever I do a serious reorg/cleanup, I make four piles outside of the room I'm working on. One is for things that go elsewhere in the house. The second is for things I want to give to specific people. The third is for donations that will go to, e.g., Goodwill. The last is for trash.

You'd be amazed at how much stuff you accumulate that can go away via piles 2-4!