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.
This part of the plan details the features and benefits of your products and services, their seasonality and life cycle, as well as any future products and services you are planning. It also includes a thorough market analysis, in which you will study your customers, your competition and the market itself. Here you should include a PEST analysis, in which you will consider the impact of various factors upon your business. The factors include combinations of the following, depending upon your business: social, technological, economic, environmental, political, legal, ethical, and demographic.
The three basic actions for growing a business in any economic climate are: improve efficiency (maintain output while reducing inputs, such as time and money); increase volume (produce more in order to spread fixed costs); reorganize the business (change goals, methods and/or philosophy). If you plan to implement one of these, you may as well plan to implement them all. By focusing on one of the above strategies, you will find a ripple effect that causes a need to address the others. This is a good thing.
Another key element to the marketing section of your business plan is an outline of your marketing objectives, strategies, and tactics. Writing down the avenues you travel in order to market your business will afford you the opportunity to record what worked and what didn't work. You must be able to measure and calculate the results of your marketing efforts, otherwise, what's the point? If you don't know if something is working for or against you, then it's working against you.