Nice stuff man, you have a great eye for creature design, especially your alien heads are awesome.
One crit would be to really focus on heads for like a week or something. Self portraits, loomis whatever, focus on construction. You have quite a good ability to draw bodies, but the heads lack a little. (oh god I know how hard heads are, I struggle like hell to still try to get them right today).
But yeah other than that man you know what your doing just keep working!