This one turned into more of a finished drawing than a sketch, although if it were really for publication there's still a bit I'd do to it. I'd likely shorten up the nose some, dress up the linework on the helmet, and work on the mouth.
I went ahead and screencast this one, too, although it took me so long I ran out of the ten minute YouTube time limit. There was a decent amount of work after the end of the video, but such is life. For those of you who are interested, here's the clip: