Although it's a novel I'm writing, and not a picture book, I'd always enjoyed those novels I'd read as a kid that included interesting little illustrations at the front of each chapter. In the early chapters of The Calligraphy of Demons, I was just finding suitable images and tweaking them a little before sticking them in there.
As more chapters were finished and posted, I started to want images that were more specific, a better fit, and more artistically satisfying. So I decided to take little breaks from the writing to do some drawing. I've posted the results on the Drawings page on my site.
Perhaps not surprisingly, the drawing is much like the writing: the more you do, the better you get. I was really rusty at first, and each illustration I complete is now more competent than the last. I'm going to do another blog post soon that explains my process.
I make no claims as to how professional the images are, or if they're worthy of being compared to the art of real, working illustrators. For me, as long as they are getting the job done, and look better than the stuff I did with crayons when I was seven, I'm happy.