Find a location with good light for a portrait shot. Place your subject some distance in front of a simple background and select a wide aperture together with a moderately long focal length such as 100mm on a 35mm full-frame camera (about 65mm on a cropped-frame camera). Take a viewpoint about one and a half metres from your subject, allowing you to compose a headshot comfortably within the frame. Focus on the eyes and take the shot.
This image was taken with a Canon EOS 5D mark IV full frame camera with a 24-70mm lens, set to aperture priority F/2.8, 1/1250 and ISO 3200.
Placing the subject in a well lit location with a fairly long focal length and wide aperture creates a very shallow depth of field, the blurred background draws your attention to the sharpness of the subject. In my view these settings are ideal for portraiture photography as it achieves a warm and natural appearance.
Jo's Photo Blog 