Female Classic Poses
Female classic poses are different than male classic poses. When posing a woman, you want her to angle her head toward the camera, turn her shoulder toward the camera and then keep her chin down so she looks thin, soft and feminine. To better accomplish this, have her point her knees away from you (at a 45 degree angle) and cross her legs or ankles away from you and then have her turn her upper body back toward the camera. Have her pull her shoulder back a bit so you are not photographing her straight into her shoulder.
Male Classic Poses
When you pose a man, you want him to have wide shoulders, so pose him straight on to the camera, angle his head away from the camera a bit or keep it straight and do not cross his legs or feet. If you want him to look more powerful, have him cross his arms and spread his feet apart. If you want him to look friendlier, have him hook his thumbs in his pants pocket.
When you are doing a classic head and shoulders pose, it is often easier to use a posing table or something they can lean on because your subject will relax. A relaxed subject will always provide a better portrait. When you are doing a full body pose with a woman, poses with her leaning are fine. When you are photographing a male, leaning poses are not the best choice.