What I've got done after an eight hour day in the studio. See below for how I started it and the step by step sequence.
9AM I'm in the studio with a plan! I tone the canvas with burnt umber as an impratura layer. On the music stand is the collaged image that is the plan. The image is a part of a larger set of images that I call my sequential narratives.
I start the painting by sketching in the overall shapes and wiping out the lights with a rag. For brighter lights I dip the rag in some paint thinner to remove more of the layer.
More of the drawing. It's very sketchy at this part. I plan on laying in layers of color and refining the drawing as I move along.
The finished underpainting painting sometime around 6 PM. Time to make dinner!