Jacqueline, with the Zorn palette, one has everything one needs to paint a great portrait. So much is true.
For those that like to mix their black rather than using black from the tube (I tend to believe Richard Schmid when he says Ivory black cracks), there’s the option to add alizarin+ viridian (or phthalo green) or ultramarine + burnt sienna to name some.
Bev, I totally understand. I can’t afford a model either.
Models are quite expensive and a good model isn’t always easy to be found.
What you could do is try to connect with local artists (maybe via a school?) and see if there is a possibility to do this in group. It’s a great way to share the costs. The hardest part is finding a location.
In the mean time, we’re doomed to work from photographs and imagination.