In general, with any industry, look for problems and figure out solutions. Alternatively, look for waste streams and figure out how to monetize them.
Specifically in Cannabis right now, if I was starting fresh, I would start out in a freshly legal market, on the ground floor if I had to, so that I could learn the ropes on someone else’s dime. Once I had built up some experience, I would look to any one of the many global emerging cannabis markets, and would move myself into position as a person with experience in cannabis startups.