The above photo is my palette showing the colors I use.  After years of painting and using a variety of other colors, these are the final few I have been using now for quit some time.  I use these six colors whether I'm painting indoors or out.  There's no need to change. With this palette I can make any color that occurs in nature.  Actually there are only three colors.  Red Blue and Yellow.  But I have an extremely warm and cool version of each one.  Listed from left to right they are, Ultramarine Blue Cerulean Blue Hue Alizarin Crimson Cad. Red Light Cad. Yellow Med. Cad  Yellow Lemon Titanium White    If you will notice, the mixing area of my palette is not white or black or even a warm wood color.  It is a middle value, non colored surface.  It's glass with a gray cloth underneath.  This makes it easier to accurately judge the colors I mix.  The brushes I prefer are Robert Simmons Signet.  I only use flats in sizes # 2-4-6-8-10-12.

On location I use an Open Box M pochade box, which seems to be the most versatile pochade box available and I paint on wood panels covered with linen or canvas.  I rarely use stretched canvas outdoors because it is too bulky, too transparent and light shines through the back which makes it impossible to see the surface.