I'm a 22-year-old who made nearly $100K in revenue on Depop last year. Here's how I did it and my secret tips to sell successfully.

• Theresa Sobocinski is a 22-year-old product designer who made nearly $100K a year on Depop. 
• She sources her items from thrift stores, SSENSE, and other popular girl brands.
• She says few people know that constantly refreshing items on Depop is crucial to boosting sales.

When I was a teenager, I wasn't really given an allowance, and I felt bad asking for money. My family is middle-class, regular people. So I tried to find other ways to make money.

I was pretty into fashion in high school, so I started selling clothes on Poshmark. But I soon realized that Poshmark takes a lot in fees: there's a 20% fee on sales over $15.