Organize your books. Make sure they're clean and free of excessive markings or damage. If you have books that have been rendered illegible due to excessive markings or damage, contact your local recycling center to find out if they can be recycled properly. Donated books are used to provide reading materials to those in need, so make sure that each book is legible. Older and water-damaged books should be handled with care as their pages may be brittle.
Contact the charity directly. There are a number of libraries and organizations that will accept donated books, but you want to make sure what type of books and amount they accept. For example, the Books for Soldiers organization collects donated books to ship those serving abroad in the armed forces, along with video games, DVD movies, and other entertainment (Reference 1). Their article "Mailing Guidelines" gives clear instructions on the proper way to mail items based on size and type. See the "resources" link at the end of this article for additional links for places across the country that accept donated books.
Mail your books accordingly. Pay close attention to the directions provided by the organization that is accepting your donation. In some cases, the donated books must be displayed in a certain fashion, so adhering to mailing standards saves the organization a great deal of time and energy when arranging the books.