If you try to make a figure transparent you'll still see bits of the teeth, tounge, etc so what I do is export the figure as an obj file, deselecting the parts I don't want or I know that will show (for example if the person is wearing a full robe, why do I need the legs, thighs, torso, whatever). Then I import it as an obj file as a single figure. There apre probably other easier ways to do it, just what I've done before