When starting a new book, I like to make sure I'm a hundred percent happy with the main character and how he interacts with minor characters. They have to have chemistry together just like actors in a good movie. I've experimented with tons of different character designs for the kids--some were shorter and more cartoony, while some were larger and more realistic. I changed the kitty (star of the show) around a lot as well. I do these quick color spots with my characters until something starts to come alive. When that happens I'm ready to go to final sketches.