One of my favorite books is "Learning how to learn" it's an older book, published in the 1970s, and one of the techniques it outlined for learning is drawing up a 'Concept Map'.
A Concept Map is exactly what it sounds like, a map of concepts within a specific discipline, and it's the most effective learning tool I've come across for studying very abstract topics like Game Theory.
Actually, I've been quite confused by the term 'Knowledge Graph', is that something that's meant to be machine readable or it's more meant to be read by humans?