staryed, i am no lover of ABA (been there doen that for 2 years to no effect) but that is just us and my boy.
However, what I learned and to give you my 20/20 hindsight, ASK QUESTIONS and point out anything you feel uncomfortable with. a good provider will explain the theory ( or as they say science) behind what they are doing.
you are his first and foremost teacher and its you that has to learn the technique, reasoning, etc before anyone else does.
I know some parents (those with money) who have left it all to the provider/tutors and have not actually worked with their child during a session. 2ndly, you get providers who say you, as a parent will be a "distraction" in the session, which is a load of crap of course.
Please try to figure out exactly why each trial is being done and what the expected outcome is, and what it is supposed to lead to.
Also, remember that each child is different. ABA, lovaas and VB were of no use to my son in the early years. He worked completely to his own agenda and I will save you the horror stories we went through with providers and their "methods".
as mommy, step in when you are uncomfortable and ask. a good provider will welcome your questions and will want you to be fully trained up and knowledgeable.
my 2cents