Ebay can be a PITA, but I've really dealt with some great people over the years. And best of all (for me) I can do it by email in writing and not verbally.
The first 3 really good sales will get you over the first hurdle quick. Then the greed will set in and over-ride the anxiety $$$.
Try to avoid using the stock photos for newer books, most people really want to see the "actual" condition.
If the books are older the more pictures the better, spine, covers, any damage or a sample of the illustrations if it has any (especially on old children's books).
I ship book rate/media mail w/delivery confirmation and offer priority as an upgrade option on the better books.
Packaging usually consists of a gallon size storage bag for water protection & either a padded mailer, or my preferred method, gallon storage bag, wrapped in b-flute or cardboard for stability, & a vinyl mailer. Lots I box, normally lined with a trash bag for mail carriers that sometimes leave packages on top of the box out in the rain.
Go ahead list a couple, then tell me how wonderful you did on them while my internet is fucked up.
You know you want to.