Soft Lighting
Diffusion occurs when sunlight or artificial light passes through a semitransparent material, causing the rays to scatter in different directions. Because soft light tends to be weak, the model can avoid squinting during a photo shoot. Blemishes become less noticeable and skin appears smooth and balanced under soft light. Placing your model in front of a window covered by a thin drape or beneath a shade tree will both provide a soft, even source of light. If you are using a studio lamp, attach a softbox to it to achieve softer lighting. Wrap several pieces of tissue paper around an external flash unit to diffuse its output.
Hard Lighting
For a grittier, more dramatic effect, experiment with hard front or side lighting. Hard lighting, such as direct afternoon sunlight or a powerful studio lamp, gives a stark, contrasty look to the resulting portrait. When the light is directly above a subject, deep shadows will be cast over the eyes and ocular holes of the subject for an austere, haunting result. Scars, facial structure and imperfections will also become more noticeable -- ideal for photographers looking for honesty or artistic merit within their work.
Silhouette
Create mood and a sense of setting by positioning your model against a bright backdrop, such as a beach shoreline at sunset or a large window looking out onto a scenic view. Have your model outstretch her arms or pose delicately to introduce motion and dynamism into the frame, or move in close for an artistic profile shot. The key to producing effective black and white silhouettes is proper exposure. Avoid metering your model, as this will overexpose the backdrop scene and result in a poor silhouette. Instead, meter for the backdrop scene and set your exposure settings accordingly.
Environmental Portraiture
Tell the viewer more about your model by photographing him in his natural environment. For example, if you're photographing the owner of a corner bodega, you might place him behind the cash register or have him stand leisurely in the entry door frame. Attach a wide angle lens, which has a focal length of 35mm or shorter, to your camera to fit more of the scene into the frame without having to shoot from a distance. Black and white environmental portraits have a timeless look which is reminiscent of classic documentary and street photography.