Whether you are looking for a puppy course or for a trainer that can help you with your dogs behavior problems here are some things to keep in mind.
1. First of all choose a dog trainer that only uses positive reinforcement methods. Other training might look like a quick fix (and believe me I desperately looked for quick fixes) but in the end they are either not ethical or they make matters worse in the long run.
2. Dog training is a rather obscure world. In a lot of countries pretty much anyone can call himself a dog trainer. It is advisable to look for the educational background of a trainer, maybe some certificates or if they are part of a bigger organization. Having said that: We had so many bad experiences with dog trainers, which had a lot of certificates that I am convinced that some dog trainers without any are more trustworthy.
3. Like in all other businesses people look for easy money. Most regular dog trainers or pet obedience schools are not looking forward to meet the “problem dog”. It's a lot of effort for them and makes their lives more difficult. Don't let them make you think you are the problem while you pay for their professional advice. Same goes for dog trainers that teach your dog their standard repertoire while you where seeking help for a specific problem.
What it comes down to: Trust your gut feeling. If at any point you have the feeling that whatever the training consists of is not helpful, challenge the trainer. It's probably because something isn't right. A good dog trainer will listen to your concerns and give you a logical explanation. If they are not able to convince you it might be best to look for someone else.
Sometimes however it's not the trainer but us. So challenge your own view as well. Are your expectations reasonable? Is it just the training or are you overly nervous, inpatient and anxious?
For example if you expect a dog trainer to fix your dogs reactivity towards other dogs than your dog will have to interact with other dogs at some point. No matter how scary this might seem at first.
A lot of times peoples anxieties mix with their dogs reactivity. We avoid problems. If your dog is reactive towards other dogs of course you can choose to only walk him in areas or at times where there are no other dogs, but this will never solve your problem. You have to face your own fears as well and you have to support your dog at the same time.
Dog training takes time! Never forget that. There will be days where you don't see the end of the tunnel and the next day they surprise you with the perfect behavior. Keep calm it's gonna be fine.