This is not something you do until you're absolutely sure you want to purge. If you do it half-heartedly, you wind up putting most of it back which defeats the purpose. This job needs surgical action.
My method is to never do it in one go. Keep a bag in your closet and when you realize that an item no longer makes you feel good when you wear it, or that you never reach for it, put it in the bag. It's not gone forever, but if you never miss it, when the bag is full and ready to donate, you can feel comfortable with your decisions.
Spunky 