For these sketchbook exercises and color studies, you'll need the following: A sketchbook, pencils, black pen, gold pen, colored pencils and watercolor pencils, markers, and -- okay -- an eraser, if you must. Also, a watercolor sketchbook, if you have one, or small pieces of watercolor paper, and watercolor paints and brushes. Try a few, or all, of these ORANGE exercises -- 1. PUMPKINS -- Draw a pumpkin, with pencil. Then, add color with colored pencil. Layer the colors, starting with yellow…