Useful Thinking Tools
Mental models are compact ways to reason about messy situations. They do not replace judgment, but they make judgment easier to inspect.
Inversion
Instead of asking how to succeed, ask what would almost certainly make the project fail. Then remove those failure modes first.
First Principles
Break the problem into facts that are still true when preferences, trends, and inherited assumptions are removed.
Second-Order Effects
The first result of a decision is rarely the whole story. Ask what the decision makes easier, harder, or more likely later.