Find the author of the quote. Once you have this key piece of information you will be well on your way to finding the book you're looking for.
Write down the quote and analyze it. Like in the childhood game of "telephone" exact words and meanings are sometimes muddled or lost when passed from one person to another. Look for opportunities for synonyms or older usage words in the quote.
Consult the quotation classic. "Bartlett's Familiar Quotations" is a great resource. This frequently-revised classic has been around since 1855. You can search by author, if known, or subject to find the origin of the quote.
Search for your quote on quote websites such as Quoteland, The Quote Garden or The Quotations Page. Browse by subject or use the site's search tool to search for specific keywords.
Take advantage of message boards and web communities. Some quote websites like Quoteland have their own message boards where you can find friendly people with answers to your quote-related queries. You can also try visiting a message board that focuses on the particular subject of the quote.
Call a bookstore and speak with a bookseller. Stores like Barnes and Noble have several different search options to help you find the book you need. They may even be familiar with the quote itself. The librarian at your local public library may also be able to help you.
Search inside the book on Amazon. This feature is available for a large number of books sold on Amazon.com. After determining the author of your quote you can try searching inside possible book matches by selecting "search inside this book." If the quote is found the results will pop up and let you know the exact page where the quote appears.