I finished a portrait this week, that I have been working on for awhile. It is 24" x 36", oil on panel. The subject is a Boykin Spaniel and his man. The Boykin's name is Willy and he is the most cheerful dog I have ever met. I first prepared the panel with 5 coats of gesso, sanding between each coat. For this kind of portrait I like a very smooth surface because the paint strokes are so small. Next I put an imprimatura over the gesso, using a mixture of Gamblin Transparent Orange and Alizarin Crimson. I thin this into a transparent glaze with Galkyd. I like to get rid of the white gesso before starting the underpainting. I then proceeded with the underpainting using Gamblin Chromatic Black and Titanium White, keeping the tonal range in a higher scale since darker glazes would be going over it in the following layers. Here are some links for more information.
http://www.boykinspaniel.org/ for more information on wonderful Boykin Spaniels
http://www.gamblincolors.com/ for more information on Gamblin colors and mediums