My experience, on the Reservation, Is very intertwined so to speak. Being in foster care in many homes, and among many of the tribes, I find certain things that resound true. There are many "superstitions" as many would put it, that lead to fear. People now, fear each other. There is strong jealousy. And there is huge mistrust, even among its own people. There is great fear of evil, and evil spirits, curses, hexes and the lot. With good reason. Before going anywhere, to learn anything, try to discern the person's spirit.
Though many do not want to believe that things exist that they cannot see, well, of course they have that right. But for many of us, who have seen into the supernatural world, just as there is good spirits, there is also evil.
I know many say, that things are neither black nor white, nor good or evil. I've heard others say, without the darkness, there can be no light, and without evil, there can be no good. I guess everything boils down to perception.
There are many who want to become "shamans" even on the reservations and outside of them. Many that want this path, do not have correct motives. They are not wanting it, because they are wanting to empower themselves, therefore empowering others. They are not wanting it, for the benefit of others, but only what it can bring them. And there are just some, who do recieve the training by right but are considered "wicked."
There is such a thing, called transferrance of spirits. (Many witches know about this, in the various pagan, earth based religions, I believe wiccan's know this also.) When a Shaman that has "turned bad" as it's simply put, and traffic in spirits, and take to the side, where their motive is to harm others, on the Reservation, we know that if they even touch someone, especially one in a weakened condition already, or like an infant - child, an elder who's health is failing, or someone physically sick, these people will just walk by and touch them, and put them at the brink of death.
Somebody then, will bring the person to a Medicine person/ Shaman/ Holy Person, whatever label you want on it, and then they go through the ceremonial rituals of cleansing the body, removing objects that are inserted in (through alchemy and certain forms of divination) or they exercise off the bad spirit. The person gets well, and then it happens all over again.
Certain families with these type medicine people, will still keep going back to them, for the most part, because they are family...and who wants to believe this about your own? right?
Hopefully, before it goes to far, they get to a true medicine person, who treats not only the mind, but the body, and the spirit, and teaches the person to protect themselves, and how to be thankful to the ancestrial spirits, and others that are there for specific purposes such as bears.
There are many forms of Shamans, and many seem to teach the same thing, just in different ways. Just discern, if you go in person to anyone who suggests they teach this kind of training because you want someone with balance, wisdom, correct motives, even if it's just for a personal level.
Loosely put, there's alot of nuts out there, and some are very cracked...
There is times, it's just wise to protect yourself first before anyone else. Difficult for a sick person, to attempt to minister healing to someone else who is sick. What's the old saying, "physician heal thyself"!!!
Dark Magus, may know some real good authors in regards to shamanism. Maybe a few others on here as well.
Brightest of Blessings.