So, although a detailed business plan may not be required for an online business, I am going to include it here so you can at least look at and consider each section and determine yourself if it applies to your business.
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).
Personnel: The success of any company depends on their ability to recruit, train and retain quality employees. The amount of emphasis in your plan for this section will depend on the number and type of employees required.
It may not be pleasant to imagine all the "what ifs," but doing it now and planning for those unexpected events will improve your company's chances of surviving a storm. For an excellent step_by_step guide on the details of developing a risk management plan, see the article "How to Develop a Risk Management Plan," by Charles Tremper at wikiHow.com.