Hey, this is nice! You've chosen a great format for doing effective pixel art; man, you can only imagine what awesome things you can do with this pallette.
I'm at work right now so I don't really have time to give goot critique, but I'll try to find time to go in-depth and maybe do an edit when I get home.
I know about the 'harsh critique' thing at pixelation, but it's mostly when people start getting defensive that pixelation members bring out the heavy guns. I don't know how I feel about that, really, but I'm glad you're not running away (:
Anyway:
Line art for the dragon is solid, although the plates on the front of the neck are a bit uneven, you might want to align them a bit more evenly.
Light source is inconsistent, look at the top horns and the bottom horns, they're shaded from two different sides. Now that I look at it I realize that the light source is supposed to be in front of him, but it doesn't read very well. Consider readability.
Colour ramps are straight and dull (not very badly so, mind you, but can get better). I'd suggest a little hue variation and more contrast.
About texture, man, that's hard, I know what you mean. Some really bright highlights to suggest scales would be nice I think. do a google image search on 'scale + skin' or 'scaly skin' and see what you find if you need inspiration.
Great that you're trying some limited pixel art, I think you'll understand what we meant about not using redundant colours if you really follow this one through (:
Cheers.