I learned this one from the fabulous resource, Jill’s Closet! I went through every single (hanging ) item of clothing I own, and pulled out anything I don’t wear, for donation or other destinations. For the rest, ones I think I wear, I put a tag on every hanger:

I cut small squares of card stock (I love my paper cutter!) and punched a hole in the middle of each one, then slid them over the hangers of the keepers-for-now.
The idea is this: Every time I wear an item from now on, I will remove the tag. A year from now, anything that still has its tag is going to have to make a darn good case for me to keep it.
Let’s see what I learn from this!