I remember sitting in front of my parents’ house with fifteen crates of books and a metal cash box which I filled with $5 by the end of the day. That’s right—a whole day of sitting at a yard sale, and I made five big ones. Don’t make my mistake!

UK members, check out Green Metropolis. You can buy books for just £3.75, and sell your old ones for £3.

US members, check out Cash 4 Books. Enter the ISBN, supply your contact information, send the book, and expect payment within three days after they receive your books.