1. Do they ask for a vet check?
Before you get a behaviourist in, they should ask you if you've had a vet check. Anyone who knows what they are talking about will know that it is not fair to spend money on a behaviourist and time on training when training and behavioural adjustment may not improve a behaviour that is based on a clinical issue. Always let your vet know of any behavioural problem that comes up and ask them to check for any medical reasons behind it. They may be able to reduce or improve the behaviour medically. For example, an 8 year old dog who has begun urinating in the house. The vet found out that the dog had diabetes and when treatment started the inappropriate urination stopped.
2. Are they qualified?
Your pet is your family so make sure that your animal behaviourist is qualified. An unqualified person could do more damage to your pet than good. They could also make a behaviour worse or could misdiagnose a problem. Try to google their qualification.
3. Do they talk about dominance?
If anyone tells you the issue with your pet is dominance...run! They are not qualified and are not using science-based methods. Dominance is often used as a blanket term do describe a wide range of behaviours which have nothing at all to do with dominance. By doing this, the true reasons behind behaviours are ignored. Sadly, dominance-based training often uses punishment which can make behaviour worse and can cause depression or even aggression.
4. Do you like them?
You will be working with a behaviourist and/or trainer for a while. It is best if you are able to get along with them, or at the very least, respect what they do. If a behaviourist or trainer makes you uneasy, rather find someone else that you will be more able to trust and work with. This is a person you will be inviting into your home and you should feel safe and that you can talk to them about anything.
So that's it. Your behaviourist and/or trainer should be qualified, able to connect with you and your pet, and should be interested in the true reasons behind behaviour so that your pet's behaviour can improve as quickly and in the best way possible.