I suggest getting a 3d deer target and as was suggested before, stick metal skewers through the target at every angle you can think of making each one pass through a central point just behind the shoulder and just below center up and down. This will help you visualize the entrance AND exit of each and every shot you can think of, so you have a point to aim for the next step. After you have done this, set the target at different angles and practice this same concept. Except use your arrows as the skewer and try to get it to pass as close to that same central point as possible while avoiding the heavy bone of the shoulder.

I can't explain this any clearer. The best way to learn is just get out there and experiment with it and learn yourself.