Randy,
I not a portrait expert, but I do have some experience with digital photography. I can tell you that one thing that will help get you to a usable pattern is to start with a clear, well focused photo that has good contrast. Fuzzy, blurry photos or those without enough contrast will be very hard to get anything decent from. The threshold command makes a lot of use of the contrasts in the picture, and good sharp focus gives the software some good edges to work with.
Hope this helps