The great photographer Ansel Adams once said: “A good photograph is knowing where to stand.”
I’ll add to the quote that a great portrait is knowing HOW to stand.
The attention to detail in how the subject poses is what separates a good portrait photographer from a great one. Everything from the hands, to the fingers, to the tilt of the head are all important to getting a perfect portrait — whether it’s a headshot, family portrait,  or professional business photo.