The best way to get an ex back is to move on with your life and be happy with yourself. Really, that's it. While I haven't read any of these books, I'm sure they all boil down to that one simple sentence.
People fretting over whether they should acknowledge the ex's birthday or not, whether they should call an ex back or not, whether they acted correctly around their ex when they saw them at the bar, whether they went NC quick enough, whether they begged and pleaded too much, whether they said the right things, etc., are focusing too much on rather minor details. Move on, be happy and enjoy your life and the chances of your ex wanting to be a part of it again are improved significantly.