Adding up all my clothing expenses of a whole year was sobering to say the least. I could've paid myself a nice holiday, or saved all that on my "will buy an apartment" account, but no, I decided to spend it on clothes and shoes.
Now I ask myself how much I need whatever it is I want to buy, and it actually works. I still shop but way less than I used to. In the same spirit, writing down things like "who needs 25 bras/15 pairs of jeans?" etc is pretty efficient too.