Make your notes is pencil. Permanently marked and highlighted textbooks do not sell for as much money as those books that have few or no markings.
Get your books on the market before the end of the semester. Students will be looking for textbooks for their next semester sooner than later. Make sure you let the buyer know what date you will be able to deliver or send the book if you market it before the end of the class.
Identify your resources. There are many online stores that will buy your textbooks, and many college servers provide a list of people selling books for sale each semester on their email lists. If the book will be used in classes at your school the next semester, find a local avenue to sell your books. If the books are being phased out, online websites will bring you the most return.
Sell right after you are finished with the book. Professors will use the most current books in print. Holding onto the book for a year will make it much harder to sell at a good price. You may not even be able to sell the book on your campus if you wait too long.
Shop at all of the local bookstores. Many bookstores on or near a campus will often buy the books back from you. There is no set amount to how much they actually have to pay you, so the refunded amount could be different from place to place. Check with each booksstore, if you go this route, and find out who will pay the most for your returned book.