Know the topic and depth of information you require. Many times there are different volumes of reference material. Some that go deeply into specifics and some that give a simple overview of the topic. Know which is right for you to avoid wasting valuable time.
Visit your local library or bookstore. The topic you are researching will determine which is a better source for you. Go to both and see what is available and what is lacking.
Wade through the different books you have found to determine which one will be the best reference for your needs. You may find several different options to consider. Take some time to look them over and see which has the information you need.
Ask the librarian or bookstore clerk for more help. Just because you found the book you were looking for, it doesn't necessarily mean it is the best option for your research. Ask one of these people if they can help you locate other titles that are related to the one you found.
Search for your reference book's availability. Almost all libraries and large bookstores have a computer to look up a title and its location. Do this and see if your title turns up. If it does not, it may be a good idea to look online.