In my previous comment i pointed to the essence that you need to focus on whether you are studying under a Master or by Yourself (harder). For actual techniques you can choose books by noted masters (eg. Mas Oyama, Masatoshi Nakayama) in the style you are interested in on Amazon. For insight/details into Martial Arts mental training and theories see the works translated by William Scott Wilson (https://en.wikipedia.org/wiki/William_Scott_Wilson).
Ever since early adolescence, I've had interest in mind-body relations/balance -- as in, how physical actions are "mental" (=thinking), and how mental actions are "physical" (=doing). So these references are really great. I'll most probably look into the William Scott Wilson works first. Many thanks again for sharing your knowledge and experiences!
South Indian Martial Art "Kalarippayattu" - https://news.ycombinator.com/item?id=41540103
On Patanjala Yoga Sutras - https://news.ycombinator.com/item?id=41538322 and https://news.ycombinator.com/item?id=41554764
In my previous comment i pointed to the essence that you need to focus on whether you are studying under a Master or by Yourself (harder). For actual techniques you can choose books by noted masters (eg. Mas Oyama, Masatoshi Nakayama) in the style you are interested in on Amazon. For insight/details into Martial Arts mental training and theories see the works translated by William Scott Wilson (https://en.wikipedia.org/wiki/William_Scott_Wilson).