I just loaded up a new palette with watercolors. This palette will be used for field sketches, mostly landscapes. It is a thin lightweight palette good for packing for travel sketching, as well. The top row is the double primaries: Hansa yellow, cadmium yellow, cadmium red, quinacridone red, ultramarine, and cerulean.
The bottom row, left, is mixed greens: bright middle green is hansa and ultramarine, dark blue greenis hansa and ultramarine, a "grayed-up" green is cad yellow and ultramarine. a "browned-up" green (red-green) is yellow ocher and ultramarine. Right, is yellow ocher, raw sienna and burnt sienna.
Below is permanent handy mixes: my favorite brown is cad yellow, quinacridone red, ultramarine; and my favorite gray is burnt sienna and ultramarine.
Notice that ultramarine travels through all these pre-mixed colors, creating a nice color harmony.