Libraries are government or nonprofit institutions devoted to encouraging reading. So, when you're researching how to publicize my book, you might pause when considering their potential. But don't shy away from the possibility because the opportunities can be substantial when handled correctly. If you already know your local library staff and have good relationships with them, their connections can help you establish a contact network at libraries in your region. Librarians are often asked for suggestions, and being on their radar helps. If your book's demand increases, they will also order more copies of it.
If you don't already know your local librarian, it's fine to call or email to introduce yourself and offer to donate a copy of your book (ideally, give them two copies). Once you've gotten to know them, you've improved your chances of being considered for the book clubs a library sponsors or hosts. Because there are more members than copies of your book on the library's shelves, you'll likely spark sales or downloads. Library staff work with book clubs or might be members and can help you network. Clubs often are interested in local authors, and finding ways to connect with them is always beneficial.
Once your book has been added to the library's inventory, ask friends to check it out or put it on hold. Creating some initial demand will make a good impression and help start momentum. Later on, keep an eye on the condition of your library's copy and offer to replace it when it's looking worn. Keep an eye out for events at your library you can attend or help support somehow. If you are lucky, some may be held in partnership with local booksellers giving you the chance to sell books or meet their buyers. You never know who you'll meet through library connections, and it's always worth exploring.
If you want to get into the collections of libraries across the country, you'll want to submit your book with a request for reviews to library and publishing industry media. Most are the places librarians go to find out about books to add to their collection. You can also check some industry websites to find out which libraries are already carrying your book if it's been in print for some time. Unlike a PR campaign that needs to happen around your book's launch time, following up with libraries and getting it into their collections can occur a bit later. Book sales are often a long-term game, and you can do well.