Online Consignment Selling: How to Use Your Phone for Cash

— -- Shawna Behrens of Martinez, California, is a stay-at-home mom who says she’s making a killing on used clothing.

“Last month I had $18,000 in sales,” Behrens told ABC News.

Behrens finds items at local consignment stores, garage sales and eBay and then posts them to an app called Poshmark.

“It was so easy,” Behrens said. “You can download that app in 60 seconds along with posting something in 60 seconds.”

“If the price is right, I’ve sold stuff in 20 minutes,” she said.

Poshmark -- along with other apps like Tradesy and ThredFlip -- offers a thoroughly social way to build and sell. Followers “favorite” your closet, comment on your shoes and attend virtual purse parties.

“You get to set the price, as well as, you know, the worth of your item, you can convey that to your customers,” Behrens said. “You can say, ‘Hey, this is how it fits. This is what I wear it with.’”

Behrens is not alone in saying she makes thousands of dollars by selling clothes online.

The online consignment industry is growing fast. Poshmark users upload over $2 million worth of items every day from their phones.

That is the equivalent of an entire department store of clothing being listed and sold each week all on one app.

Behrens says there are specific strategies for becoming a power-seller.Be Social. – “You can have live-time chats with women,” she said. “You guys can text right back and forth and it just really makes sales a lot easier and quicker.”

Be a Brand. – “I think I’m selling stuff that I would actually wear,” Behrens said.

Invest in Styling. Buy a mannequin and use it to create looks, Behrens recommends.