You should also be aware of what NOT to put in your business plan. The issue of future forecasts is a contentious one. While it's all very well attempting to make future forecasts, it's difficult to predict too far ahead. What you need is to look to the short-term future and then produce your plan accordingly. As the business plan then continues, you can modify the content as and when it's necessary. Long-term planning, however, will only prove to be a pointless exercise.
However, inadequate planning has been the reason so many businesses fail, and the rate at which they fail is overwhelming. It is usually believed that most businesses fail in their first year of operation and among those that fail, 80% of them do not have a well researched plan. It has been observed that business failure is not only connected with small businesses alone which I chose not mention here, go down too.