Today only, you can get free shipping on your first order from online consignment shop ThredUP with the coupon code SHIPAPR13. If you got the $10 credit for signing up through this link (still available, by the way!), I don’t think you can use the credit and the free shipping on the same order because they are both coupon codes. But if you have credits from signing other people up, you should be able to use the free shipping code and those.
Disclosure: This post contains affiliate links. If you sign up through me and claim your $10 credit, I get a $10 credit when you make your first order.