I've been learning to mix my own colours. I used to shy away from that, especially as every colour imaginable is readily available in tubes, but that can get expensive and I don't need to create more clutter. Also, some colours you can only get by mixing: for example black on its own is flat, but mix it with ultramarine blue and you get a soft, complex black.
This is my latest painting. Water and rocks. Acrylic on paper, 9x12 inches.
Simplicity is the removal of the useless and the unnecessary--source unknown