First find out what type of class aciton lawsuit it would be. This article explains the different types. Once you get an idea, do a quick search to see who might already have a lawsuit going. One issue may be the new diversity jurisdiction laws regarding class action suits. But you can basically just contact a lawyer who is specializing in your type of case to see if there is already a class action suit in the works and what you would need to do to become a part of it. Class action lawyers are looking for as many people to join their suit as possible, so they will welcome informational calls where as regular personal injury lawyers may make you pay just for information.