I transfer the sketch to 150# Arches coldpress watercolor paper and lay down the first washes. I used a bright Cobalt blue background knowing that I plan to mute it with opaque white later on.
Step 2 is the trickiest stage for me, finding the shadow shapes and going in dark enough, but not too dark, with the shadows and halftones. Leaving it alone to dry is my biggest challenge. Experience has taught me to walk away and go have lunch!
Step 3 & 4: Determine the darkest darks and lightest lights. I find it impossible to continue a portrait when the eyes look blank so I work on those until I have a likeness. I also found it's best to work in bright colors early on. Bright colors are easy to temper, but dull colors are difficult to brighten in watercolor.
This was the finished portrait initially, but when I photographed it, I found I didn't like the way the painting was divided almost in half by the strong light/dark values.