Here's what I was thinking for the tone/look of the dragon, it's a little rushed but you get the idea. He's an evil, greedy, badass... which I tried to reflect.
I intend to pay close attention to the overall shapes and shilouette of the dragon, as that's pretty much all we see until the money shot at the end. Most of the details will probably get lost, and the overall body shape is far more important than the head.... but I drew a bunch of heads.
The middle/left one is the only one I'm particularly fond of... it's got slight eagle look to it, which I reckon would add a nice touch.