Executive Summary - One to three pages that summarize all the information to follow; come back and write this last.
There are a number of ways of going about the process of writing a good business plan. One of the most tried and time tested ways that works well is using a business plan template.
U.S. Census Bureau (census.gov): A source for a variety of useful statistics, especially the Economic Census that comes out every 5 years.
Financial Plan - What is the anticipated income? What are the cash flow projections? What is the anticipated budget over the next 3 years? What is the break even point? When is it anticipated to be met? What funding is needed and where will it come from? What funding is currently available? What collateral is available? What is the net worth of the principals, if applicable? Possible Data Sources: accountant; accounting software; Small Business Administration; Small Business Development Center; SCORE; banks; venture capitalists.