How do you prepare your projects?

[eluser]Fero[/eluser]
Currently, my cousin wants me to create a system for him. It's frustrating to keep explaining him that "I want user authentication" is not enough information if it's client-warehouse system with several user privileges.

and that I want to know 100% what it's going to take and how much I may charge. Plus this stupid crisis and he'll expect to go down with price.

+ I want a flowchart, charts, charts, to know everything everywhere, no stress