> I recommend working with a qualified teacher in a spiritual tradition. These practitioners will have extensive training (at least decades) and will be drawing from a few thousand years of careful study of the effects of meditation (as found in Buddhist and Yogic/Hindu documents and oral traditions).
How many teachers actually have this, and how can one know that the one you’ve chosen is one of them?
I loved loopz's answer, but it's also important to grapple with the fact that you can never truly know whether a teacher is good. The path is always a risk. It's best to learn as much as you can and assess for yourself as you go.
In any event, the common wisdom is "you'll know." Or to put it plainly, do you like the person and feel like they have something to teach you?
I like the term "spiritual friend," because it's easy to understand the dynamic by analogy. How do you know one of your friends is truly your friend?
As for how many there are: I don't know. I live in the Bay Area, where the concentration of practitioners is perhaps highest in the US, and I'm aware of maybe a handful of teachers I would consider consider studying with. I'm aware of many more I would not.
How many teachers actually have this, and how can one know that the one you’ve chosen is one of them?