To add onto the fabulous information you've given, poses also include your facial expression. In this sense, models need to learn to "act" out certain emotions or learn what expressions fit with the overall theme of the shoot or the outfit. Doing this in front of a mirror as well will help round out your practice in posing. If you're having a difficult time with facial expressions, the first thing you'll need to learn is to relax your facial muscles. You should have natural looking expressions--not forced. If anything, look through different magazines and take note of the models' faces. But don't just practice the sexy Victoria's Secret pout--that gets old, quick--also know how to smile genuinely, how to laugh in a photogenic way that looks great on camera, even doing silly expressions can help broaden your skills. Have fun with it!