Imho, i think that there is no one particular thing that makes a slave. As denuseri said, it comes in small realizations. You need to be a good submissive to be a better slave. Never submit to just any Master. Get to know them first. Its ok to experiment and play, but dont become a doormat and submit to any/everyone. If being a slave is right for you it will come naturally with the right Master. You will want Him/Her to own you with all of you heart. Just my thoughts of course.