Getting the software setup was a bit of a problem. I was trying to build on the Myth computers and had an extra line in my .cshrc file that prevented pbrt from building. Once I got that taken care of everything ran smoothly.
Had issues placing the light source so that the neck and background appear dark. Sufficient patience ultimately came close to the goal. It is still a bit darker at the chin-neck border than I would like, and the background is not evenly colored. I think the light might need to be moved forward a bit, but it is quite close as it is.
Had some issues figuring out the rotation coordinate system. Having done so, it was just an issue of correctly placing the light. This took a few iterations, but turned out fine in the end.
I spent a fair amount of time placing the lights correctly. I also tweaked the colors on the lights in order to achieve the appropriate balance between the main light and fill light.
On this one, I had light placement/angling and color issues as before. I also spent some deciding which of the light sources could be spot lights, and which ones had to be area lights. Ultimately, I decided that all of them except for the accent light had to be area lights. The three area lights take a while to render.