In painting I try to stay faithful to what I see. If possible I use the sight-size method. This means that you put your subject as close to your canvas as possible, so that one can view both at the same time, without turning the head. Preferably, differences between the painting and subject are observed from 10 feet away or so. This makes comparison easy. If you can actually reproduce in paint everything you see, is another question. This method has been applied by many 19th century 'salon' painters, like eg. John Singer-Sargent.
My palette more or less consists of a warm and cool version of all primary and secondary colors (plus green). Of those, I prefer the most saturated pigments I can find. In addition I use a lot of transparent oxide red, because this is very suitable to mix greys, in combination with ultramarine blue.