All projects have levers like time, money, scope, and quality. Better know going in which of these is most important, and which ones can flex.
For some projects it is all about money. For others it’s all about the date.
You need to have this conversation up front so you’ll know, when push comes to shove, whether you are going to be able to flex on scope (preferred) or whether you’ve got wiggle room around the date.
The other thing you’ll want to discuss is: what is the one thing that would really knock this project out of the park? Is it ease of use? Simplicity? Speed? Flexibility? Safety? Write those things down and make sure they are on everyone’s radar before you start out. These high-level aspirations can be your guideposts when things get dark.