First, I couldn’t make the shape work (I started it during a lull while playing Neverwinter with my girlfriend; the dragon started off as something with wings).
Then, I got it someplace where I didn’t hate it, and actually really liked it, but it didn’t seem to be moving or anything, so I put the cave in around it, but didn’t fill in the background. The cave didn’t look like a cave, so I darkened it for contrast.
Finally, I put bubbles in, took them out, and put them back in again, because it still seemed a bit too static:
If I’d known a bit more about musculature and I guess about how bubbles work, I might have done a better job of it, but as it is, I am satisfied.