I agree 100% with enix, its a habbit I have myself when drawing, it takes a lot of effort to get away from it. Here's the problem, 1, you've got used to the same poly flow on your models imo, and it just wont cut it for such a chisseled character like Snake, he's got a lot of defining features and contours in his face that the poly flow has to match, I took the liberty of drawing out the main contours in his face for reference:
second problem is, if you look on the far right, that is the shape of a skull (placed due to your browline and skull width), unless very characterised and distorted, a skull typically will fit into a square from the side. Yours fits into a more rhombus type shape, of course this does depend on character, but snakes head is square and long, and his most dominant feature is his brow line, which is way too far backward in comparison to the jaw atm.
Take a look at some Kurt Russell pics and the original game art sometime, they're really great for refs too D:, the original game art really does well in showing the contours.