i like the dragon's details despite the few colors, although it is messy in some places. It would be cooler if you were to use the yellow in your dragon as the background color, and leave it at 2 colors. Reminds me of greek ceramic art.

 Yeah, I'm sure someone's going to ask you to make it transparent. I think it could work if you put in some AA between both the red/black and the red/yellow. Graphically, it's a cool image, just needs some smoothing.

Not bad!

I don't know if the back background is necessary in this piece... Imho it adds a good contrast, but someone of PJ may  ask you to make it trasparent...