Comment by cdhdc

This is my general structure.

* Background/Overview

* Project Scope

* Requirements (System level, or feature level)

* Requirements (The things I require from the client)

* Project Timing and Cost

* Out of Scope items or items that maybe addressed in a future phase of the project.

I found this book on writing a single page proposal to be quite helpful https://www.amazon.com/One-Page-Proposal-Business-Pitch-Pers...

I haven't ever succeeded in keeping it all one page but it is a great goal.