ejchase, do you find that you are sifting through things multiple times or are you able to just pick up each item and make a permanent decision? Are you being thwarted by a lack of places to put things?
when I started cleaning out, for a long time I kept starting at the outter surface and trying to work inward. I discovered that I made better, more lasting progress if I picked a spot and "excavated down to the bedrock" so to speak before putting that spot in order.
so, for example, I notice that I have a lot of books everywhere. Books are important to me. I decide where I most want to have books. I clear a path to that shelf and remove every item from it (temporarily making the mess worse), dust the shelf, and fill it with my favorite books. (Hopefully finding a few books and other items I can give up along the way). Now, I have one shelf that is perfect. Move on to next space/category.
clothes one never wears end up at the back of the closet, or buried in drawers. If you empty those spaces and put your favorite things in first, you quickly realize how you feel about the things that are preventing you from reaching them. When the thing you like that has been sitting in a spot forever loses it's spot to something you love and you realize you have moved the thing you like out of your way 73 times, you realize "I like this, but not enough to make space for it, so it needs to go."
also, pay attention to what you are bringing in. Try to bring in as little as possible. If things are steadily going out and you are not bringing new things in, progress is happening even if you don't see it.