Poshmark
Sell clothing closet items.
1. Free signup
App focuses on clothing and accessories.
2. Photograph items
4 photos. Good light. Hang or lay flat. Note any flaws.
3. Honest sizing
Note actual measurements. Returns rare on Poshmark, so accuracy matters.
4. Posh Parties
Daily themed sharing events. Boost visibility of items.
5. Prepaid shipping
Buyer pays $7.45. Print label and drop at any USPS.
6. 20% fee
Poshmark takes 20% of sales over $15. Smaller fee under that.
Mercari is similar. Sell anything (not just clothes). Try both.