A rule of thumb is to look for is someone with both practical experience and professional education. Find someone who can communicate effectively. Many people will try to impress you with terminology or big words. If you want to impress your friends you can always ask for the terms. Otherwise you have more than enough things to remember about how you are working with your pet and the techniques involved without complicating it with terms.
People skills are another important consideration.
In the past, people who selected animal training for a career were either not very good with people, or preferred animals to people. You will need to find someone who can communicate with both you and your pet AND teach you how to properly do things with your animal. Find someone who will teach you how to be successful. It is not wise to find someone who will do all the work for you since they will only be there a short time. It takes a very short time to change animal behavior unless the situation has been going on for a long time.