Selling Used Books

I am hoping to make some money online in various ways. One way is to sell used books through eBay and Amazon and such. I sold some of my bar exam prep books online, but I have a lot more of them, as well as study guides and other books. I also have some other books I would like to get rid of. I have too many around my house and not enough storage for them. I am not one of these people who feel they have to save every book they have ever bought. So, I could easily unload some. Would really like to make some extra cash in this way. I have heard other people talk about how successful they have been at this.