I move about every ten years, it sort of forces you to purge. My husband's parents had to move after living sixty years in the same place, it was awful. My father in law didn't get rid of anything, and put off every decision to the last minute. Just keep reminding yourself that it's only THINGS, and things are not important, your relationships and freedom to have an orderly life are far important than any material possession. If it isn't usefor and doesn't bring you joy, get rid of it, no matter how much you paid for it or who gave it to you.
I like Blondie's four box method, simple and doable. Another resource is the fly lady, http://flylady.net/. It's a forum for people that have trouble cleaning and organizing. She recommends something called the 27 fling boogie. You get a trash bag and pick out 27 things to throw away. You just keep doing that, a bit at a time so you don't get overwhelmed.