Eye of the Samurai

I did this sketch of a samurai face mask on the plane ride from San Francisco to Tokyo. Whenever I sketch in rectangular sketchbooks, I always end up with one or two of these half-a-face images. I think it's a default setting for my brain when it comes to drawing faces. I just start with the eye and work my way out. I always seem to add a lot of ornate stuff on the face (paint, tattoos, goggles etc.) and they always come out different. I would like to paint this one, using a red and black color scheme.