*Thanks Jalonso for moving this / fixing pic (yes i saw it before) winks*

Shnizel5, I know that you're asking for shading/coloring tips, but generally here at pixel joint, we like to give you advice on improving everything about your picture. so please don't take offense if I stay away from shading commets for a while.
however, This IS YOUR ART. don't feel obligated to use our comments & criticism. We're just trying to help.

Back on topic, before you start with shading/coloring, there are a few issues with your line art that need to be addressed.
First off, there are some anatomy issues (which is debatable as 'mythical dragons' don't really exist. the best thing to do is look for references.
Here is an anatomy example.
It's not the best head example, but it should give you a better idea of the neck shape, and the underlying structure of the head.

a few things i notice is the horn on the nose/snout seems big, almost like it would be too heavy. The eye is pretty high on the head, and a little backset. the (ear?) / fin thing on the side of his head, looks disconnected, and large, aswell as hides half his head. (which would be fine, but in this case, it looks like its not there at all.

after working out anatomy issues (come back and we'll help out, just keep checking in, trust us, we don't bite) you will want to clean up your lines. the noobtorials are a great place to learn about clean lines.

ONLY then do you want to go about choosing color ramps, light sources, shading techniques, and that nonsense.

I am happy to clarify anything you do not understand in my message. I hope this all helps!