I want make a discussion topic about your personal findings about color related stuff which you use in your paintings. Others can discuss and correct findings of other people.
Here are my five cents:
When Im making lights and shadow, I usually shift the hue of local color towards blues in shadows and increased saturation.
When making transition to light, hue shift towards reds/yellows, and less saturation because light washes the color a bit.
Depends also on color of light.
But things to consider are the whole color key and composition, atmosphere, etc. that you choose for your piece. But usually you don't solve these things when making concepts without any background or decided light.