There are a lot of ways that you can go wrong with dog training. You could end up reinforcing bad habits, or perhaps the way you’ve been taught to punish your pet is actually abusive and not very constructive. The fact that these bad practices are often taught and not learned, and often because they are things which have been taught by professionals for years is a pretty sorry state.
With dog training, just like anything else that you do, whether you’re looking for legal services, or dental treatment, anything; you need to make sure that you vet those providing the services. Sometimes this can be done by reputation, but it is always a good to know what qualifications they have.
The qualifications that you need to look out for for a dog trainer are primarily a dog training instructor certificate. This is the main qualification that dog trainers need, but training in first aid for pets and people are also important for group activities. If their activities are recognised by a pet professional guild then that is also another level of validation worth having.