Honestly, you did an awesome job. When I read that you bought air dry clay I was expecting a really bad result - it's notorious for shrinking and falling apart.
Even with the clay working against you, you've got a strong understanding of anatomy and the character's personality. The pose looks super classy and mysterious. Perfect for Howl. The painting is nice and subtle, and it matches his aesthetic. Having finished this guy, and him coming out so good, just imagine how cool your next project will be!
When you make your next figure, look for epoxy putty like Apoxie Sculpt, Milliput, or Green Stuff. They firm up in a few hours with no shrinking. No baking required, either. (Wear gloves, though. They can irritate your skin.)