You already know that I sell books and curriculum online. Books really are my passion when it comes to owning them or generating income with them. That's what makes it so easy for me.
Your passion may be other things - antiques, jewelry, clothes, or even tech items or automotive accessories. Whatever it is, then that's the thing you'll have the most success selling. See, your passion comes through when you write your descriptions of the items. People can read more than a dry description. They can read some of your excitement about what you're selling.
A good description that's fattened up with your excitement always leads to more sales.