What does your discovery process look like before you build a website or App for someone?

I want to know the information that you need as developers before you feel comfortable getting started on a project.

I worked as a technical project manager for a company that worked with startups and this phase was completely neglected. We ran into issues like scope creep and the startups feeling like the devs completely missed the mark and that they didn't get what the expected to walk away with. Additionally projects that were estimated to take 3 months were extended for over a year.

Any thoughts on how this could have been avoided?