I would say that you must learn the structure of the body. This means, getting grips with the human anatomy. This means drawing lots of naked people. By doing this you will learn some things. I could recommend a few books about this, like Bridgemans book about anatomy and Andrew Loomis's books. Not forgetting Burne Hogarth wonderful work concerning human anatomy.
Remember, structure will aid you in knowing what to draw.
In short, focus on anatomy and form. Gesture drawing is at the basis, then structure.