Dump everything in your closet onto your bedroom floor. All of it. Every bra, every sock, the t-shirts, all the dresses – everything needs to come out before anything can go back in. You want your bedroom to look like you've been burgled.
In the past I have sorted my wardrobe with the clothes in it and I'm not as ruthless as I should be. I'm definitely going to try it this way next time. I have a bin pile for clothes that are worn out and a donate pile for clothes that I don't wear anymore or don't fit. When putting clothes back, I like to keep like items together such as dresses, pants, t-shirts. Good luck.