I enjoy mixing a big puddle of colors for the colors and values I may use. In this puddle are Ultramarine Blue, Raw Umber, Raw Sienna, Cadmium Yellow Light, Viridian and Titanium White. I do not always set up these big puddles but I probably paint better when I do at least at the beginning. Setting up a big puddle makes it possible to create all kinds of subtle colors by picking more than one spot within the puddle. After a time the puddle will become muddy and I will make a new puddle and that puddle will vary in color some. That way the laying of colors and by leaving some underlay colors showing through makes for a better impression of the scene. It is better than painting just formula color mixes, I think.