Look through the pages of magazines. Most of the major book clubs will have advertisements in popular magazines. Specialty magazines dedicated to quilting, woodworking and other hobbies, often have their own book clubs.
Watch your junk mail. Once you get on a list, you will receive numerous offers from book clubs inviting you to join.
Look online. Do a search for a book club in your favorite genre or hobby. Most book clubs have a website for easier ordering or declining monthly selections. Occasionally, joining online will save you shipping and handling fees if you pay your introductory price with your credit card.
Ask friends or family that share your interests if they belong to a club. Members are sometimes offered incentives to bring in new members.