Unfortunately there is no straightforward way to do this, unless you're willing to travel abroad where Ayahuasca/Psilocybin Mushrooms/5-MeO are legal and do your trip there. My recommendation would be to read How to Change Your Mind and The Psychedelic Explorer's Guide, join your local psychedelic club (meetup.com maybe), and ask around. The better informed you are, the more easily you'll be able to trust your gut and know you've found someone you can trust. If in any doubt, back out. Stateside there don't seem to be very many nefarious actors, but substances are quite illegal.

If you can afford it, these 5-MeO retreats are probably a slam dunk, although 5-MeO is not for the faint of heart. Check out the psychedelic toad - hamilton's pharmacopeia for more on that.

All you really need, though, is a high-dose mushroom session with eyeshades and music, supervised by someone's that's done it before whom you trust. Their sense of attention and compassion are more important than extensive experience using them. They're just there to hold the space. Again, see James Fadiman's book for the how-to.