The 'big' idea of the paper is instead of using a light-to-no-light transition as found in the standard Phong lighting model, Gooch shading uses a warm-to-cool lighting transition. This is intended to make the details of the model visible and easily recognized even if it is not currently in the light of the scene.
The warm and cool colors should be picked out to contrast nicely. I chose to use yellow to green for this screen shot, but I have also used yellow to red or blue - pretty much any combination that doesn't produce a glaring contrast. It is also pretty cool to use two different shades of the same color - like light green to dark green. If you can adjust it just right it turns out very nicely. Here is the screenie:
I also added specular highlights as well as a nice crisp black outline. The outline was done using the extruded-backface rendering method. If there is interest I can describe the method further in the next post - I am actually planning on expanding on the NPR work that I have so far so we'll see where it ends up!