Read the description thoroughly. Examine the seller's feedback to see if you want to do business with that individual. Search for similar items currently for sale to get a sense of values. Search for similar items in Completed Auctions for final prices and to determine if the seller has sold similar items.
E-mail the seller about any questions.
Take good photos and have high-quality scanned images. Write a brief factual description covering as much information as possible. State shipping and payment terms clearly. Decide when the auction will end to avoid a never-ending process. Answer e-mails quickly and precisely.