Focus on the EYES. They are the window to the soul

Ever wondered why so many magazines have faces on the cover? It's because we identify with such pictures, which in turn helps us identify with the magazine. Art editors know that our inclination is to connect with the eyes staring out of the cover, and the same is true of your portraits.

When shooting a person, if only one part of your image is in focus, make it the eyes. That's the first place your audience will look. So long as they're in focus, they'll consider the whole image to be accurately shot, no matter how shallow your depth of field and how blurred the rest of the frame.

And in regards to eyes, pupil size plays a large part in how much someone identifies with the subject. Generally when the pupils dilate it sends a positive message and when they constrict it's a negative one. But exactly what it means depends on the situation (and whether someone has turned on a light).

I like to make sure my models pupils are as large as possible. One trick I will sometimes use is to pose the model and ask them to close their eyes and smile... then on request, "open them"... you get larger eyes and larger pupils... and generally, a better reaction to the image when someone looks at it.