I used the color picker, and saw that not a lot of them use highly saturated colors, and when they do, they use it wisely and place it in strategic places where they want the viewer's eyes to go.
I was also surprised at how they use desaturated yellows and greenish colors for the skin and use the reddish colors sparingly.
Also, subtle hue shifting. ARgh I need to work on this.
The studies I did are from Konstantin Razumov(top) and Michael and Inessa Garmash(bottom).
Beautiful!