Not every book deserves a listing. After you've photographed and described a book, your time is invested — so spend it on the kinds of books that actually move.
Current-edition textbooks, exam prep and revision guides, children's books in clean condition (parents buy these in stacks), recent bestsellers within a couple of years of their hype, and anything in a popular series — buyers completing a series will travel for one missing volume.
Classic literature in good condition, cookbooks with strong followings, and local-language fiction all sell steadily if priced modestly. They reward patience more than optimism.
Outdated computing manuals, old encyclopedias and dictionaries, book-club editions of forgotten titles, and heavily damaged copies of anything. If you wouldn't hand it to a friend, don't ask a stranger to pay for it.
Whatever the category, the listings that sell have honest, well-lit front and back cover photos. A phone camera near a window beats any description you can write.