I had a very interesting conversation with a man who described how He 'breaks' His girls. That is, the methods used to cause a new slave girl to be completely submitted to Him. Its almost like a reconditioning or retraining in a sense. one of the things He does is to bind the girl, in Nadu, naked and blindfolded, in the center of a circle drawn on the ground, a headset on her head that causes her only to hear white noise (static, and for 2 days He watches over her, she will only eat or drink what He feeds to her, she will hear nothing but static except when He speaks to her, she will feel no comfort except what he gives her. The girl quickly becomes completely dependent upon Him as she loses all track of time and her thoughts are unable to compete with the static. Her mind is now clean and completely His (of course where the mind goes, the body follows!)
Perhaps this isnt the most common method, but I bet its one of the most effective!