How to Paint Shadows in Portraiture

There are plenty of shadows on her face, ears and neck and they are all different tones and hues.

So, in the highlighted areas (i.e. the ear and forehead) the shadows are a bit sharper, with more colour in them.  I initially brush in the orange colour first, then go over them gently with my shadow mix (Scarlet and Ultramarine Blue).  If they go a bit green, add a bit more red to the shadow mix.  Don't forget, no hard edges, and soften them as they come into the light.

Under the chin where it is darker, the shadows in that area are less sharp, have less colour and lighter tone.  This area still has to be darker than the face though.  So feather off the different tones so there are no hard edges and it is soft and muted.