1. Make a Grailed account.
Grailed has become the go-to place for fashionable dudes to buy and sell used clothes. Whether you're looking for super hype brands like Supreme and Raf Simons or hard-to-find sneakers from Adidas, Vans and Jordan, a system of filters for size, brand and price make it easy to find deals. New stuff is added constantly, and there's even an iOS app so you can shop from your phone.