Back when I was in school I resold through half.com which was eBay's sister site that specialized in media only. They took a smaller cut of the sale total, and made it easier on the seller with simplified rates to offer (such as the shipping rate you had to use because the USPS offered a special rate on "media" shipping for things like books, CDs, DVDs-- anything you could fit into a special envelope they would give you). It also made it easier to list the sale because all you had to do was find the ISBN of your book, and it drew a higher volume of purchases who didn't want to deal with auctions, and liked Buy It Now used prices when browsing the online store sorted by strictly defined New / Like New / Excellent / Good / Okay / Poor conditions for the books.
Today, eBay is total garbage for sellers, it abuses you, and I don't think Half.com generates the views it used to. You're better off starting an Amazon seller account these days, and using their marketplace-- way higher volume of customer. You can also use the ISBN# to easily find and list your offering. When starting out and you don't have a seller rep rating the best thing you can do is offer a terse description of who you are, and the book. It helps to offer the best price, but even better is what you convey with this description. You're usually limited to a pretty small number of words. For example, "College student reselling to not get screwed. New Condition, but listed 'Like New'. Pristine cover & pages, no markings. STRICT TO SELLER STANDARDS."
The last line killed for me. I understood used book buyer psychology because I am a bibliophile who bought a lot of used books. All you want is to know what you're getting. In this short description, you have conveyed that you are a college student, and this immediately summons the image in most folk's minds of a child of privilege & good character who isn't trying to scam people online (or at least it used to). You aren't hard up for money. Not only that, but you have conveyed a sense that they have the power. You aren't a bookseller businessman. You are a college student stuck with something you don't want. So this evaporates the anxiety there might be something wrong with the product; there's just no need for it.
Simultaneously, it conveys a sense of seriousness, discipline, and character with regard to the obeying the rules, and conforming to the marketplace definitions. This is because some sellers, as I knew well, abused those definitions and sold "Okay" books as "Like New", or worse, "New". All you wanted was consistency and reliability as a customer since you weren't given pictures for book sales on Half.com, and this is also true for the Amazon marketplace.
I actually sold my art history textbook on that website, filled with writing and underlining in the margins, for more than I paid for it New at the college bookstore: in "Poor" condition (because a single inscription dictated that according to the rules). I made money my junior and senior year selling my friend's books for them while taking almost all of the profits. They didn't care. They were facing those same garbage $3-$7 offers for barely used, pristine $140 math textbooks and the like. I'd say, "How does $25 sound?" Pay them up front, then go sell it for $70-$110, usually, depending on the market. I had a line of friends showing up at my door with a box full of their entire college library they didn't want to keep.
