In my Life Drawing Studio class, I sometimes enjoy adding the element of color when the pose is an hour or longer in duration. Watercolor is a convenient and sometimes ideal way to go…thoughI have to admit that if the drawing aspect isn’t working, no amount of color work will make up for such a weakness, and so I don’t recommend it to students until they are well on their way.
For anyone who wishes to give it a go, I ‘d recommend starting with monochrome wash until you’ve got a mastery over wash, know your brushes and paper (which need to be of good quality), and especially the drying characteristics of your paper. I use Arches 140 lb and Saunders 200lb, which are both great papers.
My normal watercolor palette, which is primarily used out-of-doors, includes the following colors that are perfectly suited for figurative work:
Raw Sienna, Naples Yellow, Cadmiums Orange, Yellow, Lemon, and Scarlet, Indian Red, Light Red, Alizarin Crimson, Permanent Rose, Raw and Burnt Umbers, and Ivory Black. These, in addition to the blues, greens and other colors I regularly employ, are a well rounded group for general painting indoors or out.