When you draw a body from the back view, there are a few important details you should be keen on. First off, you should see definition of the shoulder blades. If you're viewing someone from the 3/4 back view, you'll be able to see a bit of a shoulder blade "popping out". Second, you should see some definition of the spine. Use short and sweet lines to bring out the beauty of that spine. Lastly, you should be able to see tone of the back muscles which trickle down to the butt crack. All of these rules apply to both sexes.