I decided to do the portrait using the grisaille (neutral grays) method. I've always admired grisaille figure paintings and I haven't tried one yet so I figured "what the hell". The yellowish cast is due to the small 15 watt bulb that I have over my easel. My wife has an Ott light placed about two feet from her head which is causing her skin tone to take on a coolish tonality which is another reason I decided to go with the gray palette. I'm working with a very small brush paying attention to each micro form in addition to the larger forms, trying to finish each section as completely as I can, as I go. Hopefully I'm asking the right questions that will allow me to paint the forms in a sculptural way rather than just matching values.