Not bad. It looks like you aren't using a general color for lights or shadows. Try using a color for lighting and a color for shadows. Keeping compliments in mind, orangish and/or yellow light with blues for shadows is usually a good choice. Only use lighting and shadow colors subtly though, otherwise it would look kinda weird. Another thing, NEVER use pure black for shadows. It looks like you did for the wings. If you must have a super dark color for shadows, go with a deep blue or just a darker version of the color your adding shadow to.
Do you have a tablet? It looks like it's colored with your mouse or with pressure sensitivity turned off. If you got a tablet it would help with your brush strokes a ton, pretty much instantly making this 2x better (and it's already pretty good). You can find a Wacom Graphire 3 off ebay for like 30-40 bucks.
Oh, I very much like the attitude that Charizard is expressing. I like it!
I would make the neck just a tad thinner as it gets closer to his head.