How do I write a proposal for a client?
Open with the client's problem in their words, then give concrete deliverables, a timeline with phase dates, the price with what's included, and a single clear next step — skip the About Us. If you can't fit it on 2-3 pages you haven't decided what the project actually is yet.
Source · Active Quora thread, many similar threads across r/freelance and r/Entrepreneur