"Choose your dog trainer as though your dog's life depends on it - because it literally does. Seek out ethical, educated and humane professionals." Annie Phenix
Training your dog should be fun! Look for someone who is approachable, who encourages the whole family to participate, and to have a good time. Someone who provides clear instructions and written handouts on how to teach the behavior(s). A skilled and professional trainer will encourage dialogue and be courteous to both canine and human clients alike. You want to be comfortable with the training tools and methods used and a skilled and professional dog trainer will spend time helping you learn the mechanical skills needed. They should employ humane training methods which are not harmful to the dog and/or handler. You have the absolute right to stop any trainer or other animal care professional who, in your opinion, is causing your dog undue harm or distress.
Training your dog in class is secondary.
You learning the process of training is primary.