Weird one, "How to talk to anyone" by Leil Lowndes, bought because someone else recommended, no idea about the scientific merit of anything in it. It helped me not just make sense of how to navigate social situations, but also how to view them as a game that can be played strategically if you need a particular outcome.

The books "Superforecasting" and "Think again" helped me nail down when and why people (myself included) make mistakes and I think it helped me prevent making mistakes or recognize mistakes others are about to make better.