Jana Parkin Essential Watercolor Starter Set
Two sets of primary colors (a warm Red, Yellow, Blue, and a cool Red, Yellow, Blue) allow you to create virtually every color for traditional subject matter, from landscape to still-life and even portrait. You'll find these tried-and-true colors on supply lists of most watercolorists.
Tip: I recommend mixing right on the paper (letting colors run together) rather than stirring them up on your palette.
Some favorite side-by-side (mingled) blends: Phthalo Blue and Quin Burnt Orange (deep, rich forest green), Cerulean Blue and Yellow Ochre (foggy skies, muted greens), Sepia and Ultramarine (rich, varied blacks).