Expanding my initial palette, adding Ultramarine Blue, Cerulean Blue, Alizarin Crimson and Viridian Green. Might not use all of them, but like to have them ready in case I decide to.
Generally I start with thinner large puddle washes and add color to them as I move to other hues. This helps the colors relate to each other, as did the overall Burnt Sienna wash as a base layer.
Below, using a large brush to add a thin layer of background color. This is mostly Cerulean Blue, with a touch of Cad Yellow Light.
FYI: I use the M. Graham oil paints. They do not pay me to do their advertising! I've just been very happy with the fact I can use walnut oil to thin the paint and clean my brushes.