Start by writing a description of your business, including what stage of development it is currently in (conception, start_up, first year, mature, exit) and your plans for growth. Discuss the nature of your business, the main products and services you offer, the market for your products and services, and how and by whom the business is operated.
I suggest that you construct easy to read tables and graphs for the financial portion of the plan. The worksheets suggested are: Salaries/Wages and Benefits, Outside Services, Insurance, Advertising Budget, Occupancy Expense, Sales Forecasts, Cost of Projected Product Units, Fixed Assets, Growth (or Start_Up) Expenses, and Miscellaneous Expenses. You may find some of the worksheet templates at PlanWare.org to be useful.
The expected revenues and expenses for at least a year should be projected in the cash flow section of the Financial Plan. It's better to make conservative predictions rather than be too optimistic when it comes to cash flows. As part of this section, a break_even analysis is essential. This is the "amount of units sold or sales dollars necessary to recover all expenses associated with generating these sales." (NxLevel for Entrepreneurs, 2005) The formula for calculating the break_even quantity is Total Fixed Costs/(Price _ Average Variable Costs).
The main thing to remember in this section is not to provide new data, but to explain in detail data that has already been provided and to provide the support for that data.