You beat me to the finish. BY OVER A WEEK x_x
Looks like you have strength mode on :]
it's really hard to proportion the helmet.
I had problems deciding how much to emphasize that chin lump, which is pretty big.
However, since people are usually a lot more familiar with the visor part, I focused more on that.
Halo was definitely easier, since his head is more long (front to back) than tall (top to bottom)