You want to be very careful not to fall into the trap of using a Caucasian and putting a brown tint on the skin. Out here we call that the "Barbi-hontis" syndrome; It's a white chick playing Indian. Also, hit the archives of the Smithsonian and the Library of Congress for facial structures as well as factual clothing. One of the things I hear from the Elders here, the few that acknowledge the Internet, is that the pictures are nice but "all that fantasy crap gots to go." Everyone has a bone to pick, a cross to bear, a political agenda these days. I think that respecting the Nations and working from the factual information readily available is the best bet. Good luck, and keep us posted on the project! I'd be thrilled if someone created a set of "real" Native Americans for Poser.