I think you need some constructive critisicm. I like the freehand ontop tho i feel it belongs better on a banner or a painting rather than this Rhino. The rest of the freehand havent got as much attention and i dont like the composition of them either. Theyre too big or blurry. I can see that if you want to you can pull this one of even better so keep it up!
This isn't about how thick the paint is! It's about the sart itself. I think it's caught an amazing feel of the renissance something I would associate heavily with the gothic and brooding Dark angels!
The only thig that buggs me outright is the skulls (well more the way the teeth sit). I wouldn't worry about it though it does take a hell of a lot of doing to get right..tis tough.
Fantastic work! :)