This 15-minute video covers a lot of ground when it comes to posing for photography. Whether you're photographing couples, newborns, or headshots, this video is sure to have information that you'll find useful. Topics range from basic composition (like the rule of thirds), to focal plane, to lenses for portrait photography.
By the way, Ms. Kelleher is correct in saying that the 85mm lens is better than the 50mm for portraits, but remember that while an 85mm lens is far superior to a 50mm lens on a full-sensor camera body, the results are different when you are working with crop-sensor camera bodies. For instance, a 50mm lens on the Canon 7D is almost equivalent to an 85mm lens. (Actually, just past the 53mm mark is the 85mm equivalent on camera bodies with a 1.6 crop factor)