As importantly, it also identifies road blocks - in advance. Your business plan should provide a common vision supported by tactical initiatives that, ultimately, creates greater value for your company. It may seem daunting, but by knowing your vision and its corresponding financial targets, you will have a better chance at executing how to get there and avoiding traps in advance.
The next thing to write (after the general description) should be your marketing strategy. For new or existing businesses, market analysis is an important basis for the marketing plan and will help justify the sales forecast. Existing businesses will rely heavily on past performance as an indicator of the future.