When I started and this was a hobby, my criterion was about the fun factor. Now that this is my career and I target a specific demographic of clientele, I use the following considerations:
1) Do I believe in the science behind the program? If there’s no scientific basis, or if the format makes claims that are incorrect or untrue, I’m not touching it.
2) Does this add to my knowledge base, not just in adding that specific format, but will it contribute to my overall teaching skills?
3) Am I passionate about this format and can I envision clients for whom it will be beneficial?
4) Will it be profitable for me?
5) How long will I be profitable before there is competition?