A few words about how I work.  I use slow drying acrylics and very thin acrylics made by Golden Acrylics.  I have adapted an old masters technique (my understanding of it) to suit these media.  First I will do a detailed charcoal(nero) sketch on the aerosol surface.  This tends to come up in acrylic washes, so I’ve taken to illustrating a dark and light comic style illustration that will withstand washes.  Over this I glaze burnt sienna slow dry.  This establishes the middle tone.  I reestablish the lights. and darks, blending them in wet on wet.  What then stands is a tricolor underpainting.  Like the old masters, I will glaze colors over this toned skeleton.  this resembles coloring a photograph. Opaque highlights follow, usually with high flow thin acrylics.  Pictured is a comic style underdrawing from a new painting.  Sometimes they come out nice.  This one I might actually redo on the computer to do a silkscreen run.