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.
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.
Include details about all of the following that are applicable to your business in the marketing section of your plan: location and distribution, and promotional strategies, such as packaging, public relations, advertising, and customer service. As a result of exploring these areas, you will naturally need to consider how much you will budget for your marketing efforts. This question is closely connected to your sales forecast, which leads us into the next section of the business plan.
If an online business, you need to go into detail how you will attract customers to your website. General statements like "I will use Face Book ads and email marketing" will contribute almost nothing to helping your cause unless you have detailed statistical analysis of tests you have conducted or of another similar business you have been associated with. If you do not have any data upon which you reference your estimates, it could show lack of proper thought to the remainder of your business plan.