I first mixed up four different values, using Burnt Sienna and Titanium-Zinc White. The final pile is just straight Burnt Sienna.
Finally, I finished off the painting with true color, adjusting values as needed. Besides Burnt Sienna and white, I also used Cadmium Yellow Light and Ultramarine Blue. The painting has a very warm feeling, so I added some areas of pure Ultramarine Blue or tints of it to add areas of relative coolness.
"Spruce Point, Low Tide" 8x10, oil, en plein air