SEO Avalanche Technique for Newbie

[redsox]

Hi all. Another newbie on board)

Thanks to a colleague, read the SEO Avalanche Technique article and learned about BoSu. The article made a great impression, started to study other materials on the forum and now I read Digital Strategy Crash Course every day as a desk book.

But... Reading is good, but applying in practice is even better. I have a question that I can't answer constructively for myself.

I have two domains that I bought a year ago. One domain - a simple drop on sports themes (was a martial arts school), the second - newreg (came up with a cool name and decided to register it) on the niche of money/psychology.

So the question is as follows, how to divide my two extensive themes into subniches, to find low-frequency keywords and follow the SEO Avalanche Technique?

I haven't been able to figure this out yet.

I will be very grateful for help and sorry for the sloppy english, it is not my native language and have to partially refer to a translator