Hi BrianRG65! When I paint portraits, I usually start with the following, and I hope this may help you on your way;
For watercolour, I start with a fairly weak Burnt Sienna. If this needs warming, I drop in a touch of Alizarin Crimson, and if the skin tone needs to be a little yellower, I use either a touch of Yellow Ochre for a more "earthy colour" or a touch of Cadmium Yellow for a brighter tone.
I would use a little Burnt Umber or Ultramarine for shadow areas.
In Acrylics, I generally start with White and add Burnt Sienna into the white until I achieve about the right strength of shade, and then, as it watercolour, I use a touch of either Yellow Ochre or Cadmium Yellow and Alizarin Crimson for balancing the shade.
These are very simple basics, and if you try these mixes to start with, I'm sure you will, by experimentation, find the best pigments for your particular portrait.
Again, I'd use a little Burnt Umber or Ultramarine for shaqow areas.
If this isn't what you're looking for, then come back to me and we'll go a little deeper.
Good luck and very best wishes,
PA & RSC Wigan area