One sketch (out of many) caught my eye as a good example of solid drawing principles:
Pure, solid drawing.
All lines lead to the head which leads down the arm, then to the arrow point, or the arrow can lead to the head. I think they're both important.
But the overall lines of action are clear.
In silhouette it's still easily readable as an Indian shooting an arrow, muscles flexing and everything.
I think it's also worth mentioning just how organic all of his stuff is. With the proliferation of anime there seems to be a tendency these days to straighten things out and sharpen corners on the human body (to streamline it):
Anime is a style, Frazetta is nature.