Since I've moved from a large room to a smaller room, the contents of my closet have been in 3-4 places around the house. But having clothes in places I never go to makes me forget that I owned the clothes in the first place. So I finally went through the closets and boxes and managed to throw out old papers, find clothes from high school to give away, and reorganize it all.
I bought large clear boxes with lids from Costco and am using them to store winter clothes and sweatshirts. I took some business-like skirts that I haven't seen since high school and hung them up in my closet, and I found some old purses, like 1930's old, and put them on display in my room. I've also started to transition the summer clothes into boxes so my closet has more room. You can already feel the change in the air. Summer is almost over.
My hope is to get the majority of my clothes into my room, but seeing as how I can't get them all in there, it is nice to know what I have and where.
What helped me to go through everything was to drag all of it out of one area and to go through it until I had gotten the floor clear again. Then I did that with the next area closet/shelf. I had a garbage bag, a pile for unwanted clothing and accessories, and a pile to keep.
If you've been needing to clean out your closet, you should take a few hours, and just sit down with it all. It's daunting, but once you're done, it feels great. Just keep in mind, it'll probably take a few hours.