Good start
Try to get your subject out of direct sun and into the shadow. There's harsh light, where the source is small and there's soft light where the source is large.
The harsh light gives you texture and shows wrinkles, pores and all the stuff you don't want in a portrait.
The soft light hides all that stuff, while still giving the two dimensional image some idea as to what the 3D object is like.
And if you can, select a clean uniform background to make sure that it doesn't compete with the subject.