Emotions. "What if..?" questions. Strange imaginary worlds. Mythologies and legends. Metaphysical concepts. But also, you know, the everyday stuff. Interesting looking trees and rocks. Strange houses. Details around my apartment. People I meet.
Nothing better than the smell of new art supplies! Music is a big factor on keeping me motivated to draw also but I'd say the most inspiration is looking at great contemporary artists and studying off of their work. I really look at their techniques and I try to imitate it in my next piece. For example I would look at the way they shade and see how they make that piece of art what it is.
sounds generic, but music inspires me. I have different bands I listen to when I want to draw certain characters of mine, and generally when I'm not listening to anything, I don't have much inspiration to draw.
I used to be the exact opposite and couldn't draw if there was any music playing. Weird how that switched around.