At present, I’m busy preparing canvasses for forthcoming classes and am wishing to accentuate the light in some of them. Can you see from the photos, that we can really highlight certain sections, travelling from black, or Prussian blue, right through to almost white if there is a light source appearing nearby in the scene.
Gesso is great for this. So with trees, leave plenty of the dark colour and build it up and up, each colour becoming lighter and lighter, until we can use off-white for leaves close to the sunlight. With waves, rather than building up and up, great effects can be achieved with simply using a dark base, only one or two colours in between and the white to indicate foam, froth and movement of light.