My two favorite books are, "Oil Painting Secrets From A Master" by Linda Cateura. David Leffel shares his secrets for making professional quality paintings. He talks about materials and techniques to setting up a still life to achieve the look you're after-light and shadows, edges, color, how to get the light to travel across the painting. One secret is Always put your center of interest in first then work out from there. There are lots of color photos. My other favorite is "Problem Solving for oil painters" by Gregg Kreutz. Lots of color photos with great still life ideas. He shows examples of what looks good and what doesn't. They also both talk about portrait painting.