I’ve trained myself to look for colours. I think of colours as having an absolute value. So flesh has an absolute value. Water has an absolute value. Metal an absolute value. To me absolute indicates solid, so the entire object is a single colour. Although that value may be present, most objects are comprised of a number of colours and reflections. If I look carefully at an object I see lots of colour gradations and colour reflections. I still tend to paint the object with a single colour initially, but that works to keep the object separated from other areas of the painting. Later I go back and add other transient and reflected colours.
At first I thought of this as being complex but it’s not it’s just the way our eyes and reality work and it really is just a couple of brush strokes. As I’m progressing on the painting I don’t try to mix exactly the same colour for each painting session. Minor variations and a few judicious brush strokes add to the reality illusion. I think that everything must have a basic colour. It translates the light hitting it into that colour and that light colour is what illuminates and reflects on other close objects. I think I got this pretty early when I was learning to paint and I still paint an object then look around for other places to add the same colour. This has the benefit of pulling the painting together and adding to the reality illusion.