Everything I know, I learned from /r/churning. Although it can be pretty intimidating as a newbie; I was a lurker for a ~year before I was comfortable enough to start hitting SUBs.
As far as general advice, many people acquire Chase UR points predominantly for Hyatt and acquire Amex MR predominantly for flights. If you're in 2 player mode then you earn points a lot faster because you can refer each other.
If you're specifically interested in Japan flights, I recommend checking out this podcast: https://thedailychurnpodcast.com/ep-58-how-to-book-ana-japan...
As far as general advice, many people acquire Chase UR points predominantly for Hyatt and acquire Amex MR predominantly for flights. If you're in 2 player mode then you earn points a lot faster because you can refer each other.