The best way to become a dog trainer is to find a trainer near you to apprentice with. You can search for a trainer at http://www.apdt.com If you choose someone who has a CPDT-KA after their name it means they have passed a written exam on dog behavior and training, so that would be good. Ideally you can find someone who uses humane methods based on science, not made up stuff like some of the things you see on t.v. Often times it is beneficial to attend a trainer’s class with your own dog or a dog from the shelter or a rescue organization. That way you can decide if you like their methods and would want to work with them and learn from them. Best of luck to you.