Some watercolors are interesting in the way they granulate. They kind of paint themselves.
Burnt umber is one of those, here is an example. Neutral tint is another interesting watercolor pigment.
I have long wondered how to mix the color of spruce in the early spring as the snow is shimmering and the sun is shining strongly.
Green but not green. Dark but not black. The color becomes more of the opposite color than local color.
Here the color of spruce is the mixture of viridian green and permanent magenta.