It started out like this. Made a quick sketch in my computer and made a rough layout so that they can more or less see how it's going to look like.
After that I started drawing and coloring the characters. During the process, I found out the joy of using a Wax Crayon brush in Photoshop. You just have to tweak it a bit and it's good to go. That will be my new favorite brush!
Then I rearranged everything on a final document, adjusted the colors, added textures and so on. Here's the final poster design/illustration:
That's all for now!