Large projects can be largely successful; however, there are many ways for any plan to fail, and the likelihood that something will go wrong increases in direct proportion to the size of the project.
By planning your project properly, you greatly increase your chances of success.
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.