This is intended as a short introduction to selling first edition books and more desired hardcover and paperback first editions as well as collectible editions. I have been collecting and selling used books since 1974. I specialize in SF and fantasy, horror (ala Stephen King, Dean Koontz, etc), military non fiction, serious religious scholarly books when I can find them and vintage paperbacks. I have sold at least 2,000 books on eBay.

I have found eBay a great place to buy and sell books. I claim no vast expert knowledge as  book collecting has so many diverse categories but here are some general observations .

As with any collectible condition is king. One can sell a fine to mint condition book for much more and without question then lessor grades of condition. Many selling on eBay seem to feel that stating something like "looks good" or "good shape" as their condition pronouncement is enough and often there is no picture of the item! This is the internet. Barring strong feedback in the thousands all a bidder has to judge is what you write.

I try to over describe flaws in detail and include scans of those flaws. I have had a handful of returns for condition but those are often due to postal delivery damaging of the book. I once sold on eBay a 1938, first edition Dr. Suess book. In mint condition, with a dust jacket this should be between $1,000 and $2000 depending on the dealers price. But mine had no DJ, was in good condition and had the last four pages colored on by light water colors.

I scanned those pages and made sure that they were in the description. I also wrote a detailed explanation for any potential bidders.

The better the condition the easier it is to sell.

Learn to identify first edition books. The words first edition or seeing a 1 in the number line are not always indications of a first edition. There are books on how to tell true first editions.

Age has no bearing in the value of a book.  Just because a book is old does not mean it is valuable. The popularity of the title is more important then age. Harry Potter first editions will often sell quicker then just a book because it is old. 

When the Peter Jackson films were out  J.R.R. Tolkien items were hot and now they are not as hot. Yes, a first edition Hobbit or LOTR volume will still sell easiy but when the films were out there were thousands of items up daily. Do a search now and no where near that many come up. Look for the trends in pop culture and find books to go along with them.

Protect the book when you ship it. I have received so many items off eBay which were poorly protected. A seller should pack a book so that it can survive the ravages of the postal delivery system.

These are just some thoughts of mine. Good luck!