Read: things you disagree with; spy-stuff -- like soviet defectors to the West; detective novels; about applications of game-theory -- like how to win at poker.

There are a few ways to get you going:

- The "5 whys"

- "First Principals thinking" (popularized by Musk),

- Challenge and validate assumptions

Read as much propaganda as you can. The more opinionated, the better, but be sure to not miss one side.