Working in Oil

I'm exploring oil these days and am still on my kick of painting portraits and figures. This image I tried my hand at "grisaille", which is painting an underpainting of a monochromatic hue. But I was recently in a critique where the fellow members talked about how grisaille was often done with warm tones, such as sepia or sienna so that the glazing that took place over it was also warmed (specifically in portraits). I think I may re-do this in a warmer hue. Stay tuned for more oil on linen.