Very good for a first real picture.
Don't worry about overspray. I've been airbrushing for a year now, and I still can't spray freehand without any overspray on a hard surface.
I've been using stencils all year long instead of practicing freehand. So the result is that I will really need to practice it now...
That's a very nice painting indeed. You're making me jealous
Gilles