• Start off the painting by holding back from going too dark at the beginning. You can always go darker or lighter later on, but for now, practice restraint. I like to start off a value or two lighter than my darkest dark. Treat the lights in the same manner, painting them a value or two darker than the final value you plan to end up with. I'll lighten things as I go, saving the darkest darks and the lightest lights for the very end. Remember to simplify you values. I like to brake things down into 3 elements. You only need to be concerned with darks, mid-tones and lights.
• Get a feel for transparent paint and opaque paint. At the beginning of a painting, I like to start off with washy/transparent paint, using turpentine and/or linseed oil--or just Liquin. As I develop the painting, I progressively use less medium and get more and more thick with my paint strokes (using little to no medium toward the end when I'm gobbing on my highlights). I'll try my best to preserve my darks. However, if I do go back into them, I do so with transparent paint. Thick paint for the lights and transparent paint for the darks. This way, when the painting is completed, the dark brushstrokes won't catch the light that is shining on the painting and the light brushstrokes will.
• Tip for how to paint glasses: I like to paint them in toward the middle/end of the painting after I have my basic features of the face blocked-in. Reason being, I can paint the skull structure and flesh in first without having to worry about the glasses getting in the way. And after putting the glasses in toward the end, I can then afford to paint around the outside of the glasses, if needed. This allows me to redefine varying edge intensities around the rim of the glasses and more accurately render the thickness of the frame, if needed. As a final touch, I may add the shiny highlights of the glasses at the very end (if they're not too distracting and don't take away from my overall intent of the painting).
