I started from a shop.
I was searching for a "contact juggling" ball and saw a kendama promotion video in the shop.
It was clear quickly that I'd learn this toy now by heart, too, after this video.
Then I got a few used ones and started to play 1-4 hours a day, along with my dogwalks, using both hands so far, for each trick until it worked.
It is a perfect toy for a walk...if you practice it with both hands, then you are training and strengthening both parts of the brain...