Locate the ISBN number. The ISBN number is found on the back of most textbooks. If it is not located on the back of the book, check inside the back and front covers. The ISBN is a 10-digit number individual to each title it is issued to. Most online companies use the ISBN number to identify the textbook you are interested in selling. The volume and version of publication is different for each ISBN, so it will have all the data it needs.
Shop three to five different textbook sales sites such as Valore Books and Amazon.com (See Resources section below). Different sites can offer different prices for textbooks based on the demand of their particular clientele. Don't try to figure out who they sell to, just check each site prior to making a sale.
Decide on direct sales or facilitated sales. Sales to companies like Valore Books are direct sales to the used textbook company. You enter the ISBN and receive a direct quote. If you decide to go the facilitated sales route, you can sell the textbooks directly via Amazon as a used textbook. You'll be responsible for the shipping once Amazon contacts you that the textbook is sold and you've received payment and shipping.
Sell the textbook online once you've shopped the price and decided on the method of sale. Direct sales to companies like Volare may not get as much money as a facilitated sale via Amazon, but you will receive payment for your books faster.
Keep track of your textbook sales. You may need this information for tax purposes. You can often claim the difference between textbook purchase price and sale price as a deduction.