To hold a painting together visually, we choose 2 cool colors (blues, purples, greens) and 1 warm color (yellows, reds, oranges) for cool color dominance, or 2 warm and 1 cool for warm color dominance. Echoing the colors pulls the painting together.
Above, the cool dominance is the blues, blue purple, etc. Below, the same outbuilding and chickens using orange, yellow ochre, and a cool blue to demonstrate warm dominance. I mix my colors right on the paper.