Plan for the worst-case scenario.

Consider the worst-case scenario and take steps to avoid it.
To get an idea of what could go wrong, consult someone who has executed a similar project in the past.

Base all your decisions regarding the project on a rational weight of gains, losses, and probabilities.
Don’t fall into the trap of delusional optimism—a poorly planned project will always fail. On the other hand, planning your project properly will greatly increase your chances of success.