Hey, I like it. The detail on the armour and bow are cool, and the previous wyrm-thing was nice. I'm a drawer of bows and wyrm-things too, so I can appreciate such things.
Here's my advice:
If you're not using one already, find a graphics pen and learn to emphasise key lines with it. If you are, then you need to adjust your scanner contrast and brightness; I found the pics a little fuzzy, to be frank, although I have much the same problem with my pen/pencil work.
Also, try adjusting the posture of your humans a little; the details are excellent, but the overall shape looks slightly unbalanced. Try positioning the feet further under the torso. As it currently stands, the guy would be slowly toppling backwards under his own weight. It's a VERY difficult thing to see, and it took me a while to spot, but if you sort it it'll tighten up your drawings no end.
As for fire, I haven't actually tried fire without CGing it. I guess you'd want the absolute minimum of work on it, especially in dark areas; you need the fire to be as white as possible. Also use consistent shadows and lighting to imply the fire's brightness in an area. Smoke and embers should probably be mere suggestions, although smoke will eventually thicken up.
Hope this helps!