Welcome to The Art Of Posing Part 2 - Structure
If your legs and feet are the foundation than its posture that are the walls of the posing structure.
The spine and the string. You want your posture to be good so your back should be straight, but not look like you are standing at attention in the army. Think of an imaginary string straight up and down but relaxed and floating, not tight, taunt, stiff, and immovable. The simplest is to stand up straight then drop your shoulders
One final touch is to bring your shoulders back about 1 inch. This conveys confidence and beauty.
Of course there is always the exception to the rule. Leaning requires good posture at an angle. You do not want straight and stiff spine. But a gentle natural curve. If the hold the string and lay one end of it down its creates a gentle curve instead of a sharp angel. You want to do this with yourself. A natural, comfortable, relaxed leaning curve that looks like it is normal and not specifically posed.
Come back tomorrow for learning the important details of your eyes and your hands