When I can, I like to "get away" with adding thick intense pure color into reflected light (under the nose and chin for example).
So often you can "hide" a bright pure color in plain sight - and nobody will notice it until you point it out.
In my Portrait of Zabie, above, I have added a brush stroke of pure cadmium orange - straight from the tube - underneath her chin.
I define "pure color" as a color without any addition of white to "dilute" it. Instead of adding white, I usually adjust the value (lightness or darkness) of this color with something lighter - usually yellow ochre pale in order to allow it to blend in with the surrounding tones. I am talking about thick paint here - not a glazed color.
I prefer to use the warm colors from my palette - reds, yellows and cadmium orange. But there is no reason not to use the cool colors if it serves the image.
Pure color can greatly enliven and enrich a painting. I try to find as many excuses to use pure color whenever and wherever I can.
Reflected light can be "toned down or neutralized" a bit by mixing two color opposites (i.e., red/green, purple/yellow) if necessary. If a cooler color is required, you can add a dab of white and/or blue to "cool" the mixture. Sorry, I do not have an example of this handy.
Note that if you're not careful, you can lighten an area too much and run the risk of fragmenting a solid shadow - always a no no.
Although the accepted knowledge is that "reflected light" is actually reflected from a color specific object nearby, I seldom pay much attention to this.
I say that whatever color looks good and you can get away with..go for it! Painting is not meant to be reality. "Reality" is mostly the task of photography.
Detail of my Portrait of Elizabeth Brewer. I used a streak of nearly pure cadmium orange both under the chin and in the earlobe on the left.
Detail of my Portrait of Whitney. I have added more yellow and a touch of blue here in order to tone it down.
A detail of my Portrait of Gwyneth. I used a little more yellow to tone it down under the nose and chin to avoid overpowering those delicate skin tones. Toward the ear, I used straight-from-the-tube undiluted cadmium orange.