if its of any interest I did a bit of web-research inspired by this thread.
what I found out is by no means definitive, I looked at generic information and specific stuff about Iroquis, Seminole and Commanche tribes (also other Plains Indians) and there seem to be alot of consistent repetition of colour theme and application.
"Except for black, which was the color for war, there was no standard
color or pattern for face and body painting: it was a matter of
individual preference. For example, one warrior might paint one side
of his face white and the other side red; another might paint one side
of his body green and the other side with green and black stripes. One
warrior might always paint himself in a particular way, while another
might change the colors and designs when so inclined. Some designs had
special meaning to the individual, and special colors and designs
might have been revealed in a dream."
and
"face and body painting was a matter of
individual choice and helped a warrior attune his mind for battle.
Faces could be striped or spotted in one or more colors or painted
uniformly. Bodies were colored in the same manner with a paint and
grease mixture, often with patterns of bold wavy lines.
Old wounds were often highlighted in red paint"
red - colour of war - represents blood (commonly used in bands or stripes on the face, the backs of hands, on wrists and knife handles)
black - a "living" color, worn on the face to prepare for war (seems to be applied similarly to red)
yellow - colour of death, represents old bones - worn for mourning (some suggestion that it might also be used for war)
white - colour of peace
green - mostly painted under the eyes to give night vision but also used generally.
"He then called for his red paint, and his looking glass, which was held before him, when he deliberately painted one-half of his face, his neck and throat, -his wrists- the backs of his hands, and the handle of his knife, red with vermilion; a custom practiced when the irrevocable oath of war and destruction is taken."
"Several of the Indians' fighting techniques were calculated to strike terror. Some warriors entered battle naked except for a loin cloth, but their bodies were streaked in bizarre examples in red and black paint... (In council) there might be a half red circle of paint under each eye and silver rings in the nose. A few famous braves had their ears elongated and slit."
"Yellow paint says a warrior is ready to die. Red war paint signifies blood; green under the eyes makes for 'see better at night.' Yellow, the color of death, means a man has lived his life and will fight to the finish."
I'd take some of this with a grain of salt, and then of course there's artistic license when painting your own figs anyway
,but at any rate I hope some people find it useful when painting native american warriors.