While photographing models, I've been fortunate to learn a fair bit regarding the basics of portrait photography. As photographers, we always try to make people look their best. We're not plastic surgeons in any way (though it would be good if we were), but we use the aid of lighting, posing, composition and even the liquify tool in Photoshop to make our clients look their best. And one of the best techniques to master is how to make our subjects look slimmer. This is particularly an issue in Western countries where more 'overweight' subjects are more commonly encountered.
Shooting from a slightly lower angle with a wide lens (24-28mm would be ideal in my case) makes their legs appear longer than they actually are, and it can appear quite elegant.
It's easy to make legs look longer when they're in a standing position. I know more intensive photoshop work would be required to make the legs more spectacular.
On a separate note, this stance, with the model's weight on her front foot and one foot crossed over the other is contemporary and natural looking (though some may disagree with me on this matter). The space created between the arm and torso, and also between the legs allows the eyes to travel to the background and makes the model look slimmer. Turning the subject at a slight angle to the camera makes her look slimmer too.
If you 'fail' to position the subject at a slight angle away from the camera, she will look more confrontational, and the broad shoulders don't capture the feminine essence of the subject. Taking a relatively tight shot with a telephoto exaggerates this problem too.