Think about negative spaceUsing negative space in your drawing makes an amazing difference - it forces your brain to really work, and helps you to draw what you see more accurately. Note the shape formed between the ground line, legs and body. Even when you don't have enough boundaries for a defined negative space, the angles formed between parts of the body and a vertical or horizontal are very useful.
Pay particular attention to the line along the top and bottom of the head, the angles of the neck, and the slope of the back. Look for key shapes within the body, such as the slope of the shoulder.