Buildings (step four)
Learned while painting the color gradations on the building: the brush picks up color from the canvas as well as laying it down. When it’s dried just enough before you start, this can work out great for laying down color gradations: The whole area starts out with color A, then you start at one end with your brush full of color B, and as you work your way across the color on the brush mixes with the color already on the canvas.
It’s probably a terrible technique; I should really be mixing colors on the palette instead. But it’s very satisfying (and quick) when it works.