Do your research. In order to be able to write a strong, comprehensive business plan you need to possess a sound knowledge of the market you are involved in. You need to actively conduct market research and ensure that your plan makes reference to your findings. It should include factors such as market size, the predicted growth path of said market and how you propose to gain access to it. For example, if you are planning on opening a bar then your business plan should include figures based on the local population, cost of suppliers, predictions about whether the bar industry is likely to grow or decline in the area and a review of the competitive environment.
Once you have done all this you should have a complete and detailed professional business plan. The most important thing to remember when developing the plan is to see it as a living document and include specifics regarding dates and specific responsibilities. Your plan will need constant reviews and updates and things change so expect it to be a work in process for a good stretch of time. It will all be worth it in the end, a well-written plan will help ensure that the business is fully focused on what is required to achieve the company's goal.
Financial Plan- This is the most important part of the business plan where you need to show the three year projection of the projected financial statements, including income statements, pro-forma balance sheets, and monthly cash flow and annual cash flow statements which will help in forecasting your revenues and expenses.
Products and services-You should list down all your products or service offerings and highlight how it is different from your competitors, its basic features and advantages and in what way it will benefit your customers.