So, how does an artist choose subject matter for his next digital painting, and what style do you use? This has been a topic I have been mulling over lately. Basically, I use my gut instinct when painting. When painting Hellboy, I wanted to use a bold style with good lighting. With the Turtles painting, I wanted to paint something a little more "gritty," but with pretty much the same bold style. Aragorn and Arwen deserved a little more realism, so I pretty much went with the painted look.
I'm now working on a Harry Potter painting that includes Prof. Dumbledore and Fawkes the phoenix. I'm really going experimental on this one, making it look more like a watercolor painting than anything. And, that's fine. But for the TMNT? I don't think watercolor would have worked.
I have seen many other styles work very well in digital paintings, but most other digital painters have one style and stick with it. I like to experiment, to try and pull out of the painting the most aesthetic work that I can. If watercolor works, I use it. If the subject requires a more cartoony, smooth feel, then I go with it. If it needs a style that is more serene or surreal, I'm using watercolor. Don't be afraid to test your limits. As an artist, if you limit yourself, you're placing a mental block on your work. And that's not something you really want to do.
So, what makes a good painting? I guess I'd say to paint from the heart, paint what you know, and always experiment! :)