Let's start with potential. The business has to be big enough to be worthwhile. The business has to be in a market with significant potential to attract talent and capital.
Then there's people. "As a member of a startup, you're the head cook one minute and and a bottle washer washer the next. However, you need competent people to handle their respective roles.
Thirdly, priorities. You will always be short on time, short on people and short on runway. Make sure you have milestones and interim check points, and have those priorities calibrated.
Note: largely pirated from a vatorTV video.