In play settings I usually have people refer to me as "Sir"; I feel very strongly that no one has the right to call me "Master" unless I have collared them.
I have identified as a Master for the last 15 years, before that I identified as a Dom for 10 years.
I am currently in several relationships; my primary relationship has been ongoing for about 18 months, it continues to evolve and is currently difficult to define. I also have a long term play relationship with someone who is both a friend and a regular play partner. In addition to these, there are a couple of new play involvements which are to simply to new to be defined at this time.
As for training, in my early years I was mentored by many very skilled and knowledgeable people in everything from the physical skills involved in BDSM to the mental aspects of D/s relationships to the development of the self discipline needed to do these things in the way that seems best for me.
I am currently in a 24/7 live in relationship with my slave.
I have not had any special Master training. I have learned threw watching those in the community that I respect and admire. You can call me Cup Cake.
I will play punish in various ways but that is a different matter.