Underpainting, or Dead Layer

So there you go, I finally got the digicam I wanted to get :-) Really cool deal, and a 5mill pixels too!
After filling my eyes with the Dutch Golden age paintings, back home and during the first weekend I took the courage and painted the dead layer. This basically consists of a monochrome rendering of the first drawing.
Medium here is increasingly fat: 1 part of stand oil to 5 parts of turpentine. Didn't use the fan-brush as I have a big one that would spoil everything - where needed I used my fingers (and it shows :-(
I wanted an overall warm feeling to the final colors, so I opted for Raw Sienna and Burnt Umber. As you're not to put in the highlights, but only achieve the light effect by scumbling, this is somewhat limited.
The shoulder blades are way wrong, as some other shadows, not sure if I'll be able to correct it. It will require some thinking alright. Next layer (grisaille) will allow some white, while keeping the monochrome effect on the two previous colors only. I hope most problems can be corrected there - fingers crossed :-)