I've purged my closet twice already.
My rule is if I can take pants off without unbuttoning, they need to go. Shirts go if I can grab a fistful of fabric on the side.
I'm actually shocked at how many clothes I had, and how well I'm managing on my limited cheapo in-between wardrobe. I kept 1 pair of jeans, and I can't bring myself to get rid of my "before" cashmere sweaters. I'm too cold to stop wearing them, and too cheap to buy new ones yet, but that's another story.