"Trust smart people and don't interfere with their work."

Bill wasn't afraid to hire people smarter than himself. For example, his partnership with Paul Allen (one of the founders of Microsoft) and Steve Ballmer (ex-CEO of Microsoft).

"The first rule of any technology: if it makes business more efficient, use it."

Back in the 90s, he demanded analytics for every bug, every customer, every market. His famous "Think Weeks," when he would isolate himself with folders of reports for analysis.

"If something is going well, something else will definitely go wrong."

In meetings, he often took the skeptic's position, asking tough questions. This helped identify risks before they materialized.