Portraits should look natural and pleasing. Natural light is difficult to get to grips with but is a speciality of theirs. Black and white is becoming more popular and sometimes captures that moment exquisitely. Even with flash photography it is important not to blast a subject with light and lose the detail.
If using a studio set up to take your portraits Martin and Amber ensure only one light source is seen in the pupil and will provide light to emphasize the subject and not blind you!