For instance, in my Buffalo Hump novel, much of the Nez Perce character was developed due to knowing a high school friend related to Chief Lawyer. I didn't help him much with tribal customs when we hung out together. In my Hollow Point novel, I blended information from several Salish folks. Some identify with the Suquamish tribe and some less so. Identity is an issue that the Elders try to bridge with the young all the time. That is where my character originated from - that identity struggle.
In another manuscript I'm starting on, I came across a young lady who coincidentally is back in Browning, Montana as I'm writing this to make her annual visit to her grandmother. She is half Blackfoot and Browning is the Blackfeet Reservation's main town. She knows people who have stories. I look forward to her return.
Beyond personal contacts, I'll bet I've read more information on the various tribes than I have read in any particular subject matter other than Paramedic Certification. The great part is how edifying it is to learn why certain things came to pass in today's world. Many are no different than other cultures' growing pains, but our Indigenous friends often have some unique traditions that most non-Natives don't understand.
My goal is to write a good fiction novel and blend in some of the tales and traditions of the tribe I'm focusing on and give the reader a new point of view and, contrary to the rumor mill, I do not use arrows to shoot at targets with character traits emblazoned on them. That would be tacky and risky for anyone standing within 50 yards of me (but a good source for another story!)..