How to Get Good at Game Theory

The future is essentially unknowable, at least in certain realms and to certain degrees. How do you get good at or better at knowing what someone else will do in the future? If you can read about smart people and how they've done things, that is another way to learn. What is the cheapest, most nutritious and bountiful food that has ever existed in history? Technically there are pickles, so I think vegetables has meat glue.