There is value in doing an ample amount of preparation prior to creating a business plan: you construct creative solutions to complex problems. Make sure to take the time to do the job properly. Additionally, be sure to keep detailed notes on your sources of information and on the assumptions underlying your financial data.
Second, your business plan should be a tool you use to run and grow your business. Something you continue to use and refine over time. An excessively long business plan is a huge hassle to revise—you`re almost guaranteed that your plan will be relegated to a desk drawer, never to be seen again.
Things like: Could you grow faster with more money? What are your headcount assumptions? How much are you spending on marketing expenses? What are you assuming for payments and collections lags?
Later, as the investment process proceeds (if it does), the latest regularly-revised plan will serve as a companion piece to the pitch and a key document for due diligence.
Highlight the key aspects of your financial plan, ideally with a chart that shows your planned sales, expenses, and profitability. If your business model (i.e., how you make money) needs additional explanation, this is where you would do it.
The executive summary of your business plan introduces your company, explains what you do, and lays out what you`re looking for from your readers. Structurally, it is the first chapter of your business plan. And while it`s the first thing that people will read, I generally advise that you write it last.