Find a location with good light for a portrait shot. Place our 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.
Focal lengths appear to compress space, giving a shallower depth of acceptable sharpness, which is known as depth of field. This makes a short or medium telephoto lens perfect for portraiture: the slight compression of the features appears attractive while the shallow depth of field adds intensity to the eyes and ‘lifts’ the subject from the background.
The first image shows obvious grain as this was taken at 300mm but the effect has been achieved and the background has softened allowing the subject to stand out.
The second and third images were both taken at 58mm, f4.8 , this has enabled the subject to appear sharply against the softened background and appears to ‘lift’ the subject. These two images are much more successful and you are drawn to the subjects eyes and face.