I do know instructors in Livermore that I have had lessons from and found great!
I do highly recommend. Dana Estes, Sandy Boling of Vineyard Eventing for English, Dressage, Jumping. I also recommend for Western Tracy Maurer. There are many other instructors in Livermore that are excellent.
Boarding I have had my horses at Rancho Cerro located in Livermore and Airdance located in Livermore.
You must do your due diligence and come to your own conclusions what are best for you, your family, son or daughter, as to riding lessons.
This site contains what I personally found for myself useful and some opinions on what I consider safety and looking for a horse. Again, you must go to a professional and ask their advice.
Also note my experience is limited to Livermore and only a few of the many wonderful facilities and instructors.
The hard way is ignoring your teacher and treat your horse as a dog!
Did you ever notice the difference between your dog stepping
on your toes and your horse stepping on them?
Answer: Horse really needs to stay in his own space and your toes need to stay in their own space