What do you do to ensure your project is on or below budget?

"In my experience, planning beats mitigating, when it comes to budgets. It's always best to over-project the budget at the beginning by accounting for common budget overrun culprits like longer-than-expected labor hours, or unforeseen changes. This way, I have a Plan B or Plan C when they do come up. When they end up worse than projected, I can inform stakeholders as soon as I identify the risk. At the beginning of a project, I don't know what I don't know, so the best I can do is look at similar projects and prepare a plan for the worst-case scenario."