One of the things I've talked about most with other masters, is training and games. Some seem to believe training to be a serious business and others aren't really sure how to go about it. My personal approach is to use games. I've always figured that if I'm not having a good time I should be doing something else. This philosophy has taken over my life, I work this way, play this way and treat my slave this way.
My favorite game is the penny game. This can be used for training a slave to stay in any position. I will list my favorite position here. It's a modified Nadu.
You need to find a linoleum or tile floor. This doesn't work on carpet. Your slave kneels before you knees spread, hands behind the back fingertips and thumbs touching. Between the finger tips and thumb tips you place pennies. Now the fun begins. Start tickling or playing with your slave. I enjoy both at different times. For now lets go with sexual stimulation. This helps teach your slave to remain in position when excited. As your slave gets more and excited they will lose concentration. When this happens one or more of the pennies will drop. You'll both be surprised at how loud this is.
Now first and foremost stop stimulating your slave. Let them stew in their own juices. Now the type of punishment is your choice. Not all punishments are effective with every slave. Some like pain and will enjoy the spanking, some love being exposed and cornered etc. Pick the type of punishment you wish to inflict and inflict it.
Practice does not make perfect. Perfect practice makes perfect. So as soon as your slave is done with the punishment repeat the game. You may play this as often as you like. I've always found it to be a fun game and my slave loves the attention.