The internet is a fantastic resource for writing a business plan, but for some people, nothing beats a good old-fashioned book. Your local library has entire sections dedicated to the multiple aspects of business development, and you can be sure to find several books about how to write a business plan. Best of all - these are free! If your local branch does not have the book you're looking for, check the catalog and request a book transfer. Sometimes, the perfect books about writing an effective business plan or ideas for a sample business plan are just an inter-library loan away.
A business plan is essential for all businesses regardless of size, and once one has been written it is also important to maintain and update said plan. That being said, it is important to realize that whilst writing a detailed plan is useful and a good foundation for any successful business, it will not necessarily make the business a success or guard you from all disasters. If you keep up to date with business plan it will prove a really useful tool throughout the lifespan of your business. However, if you grossly over exaggerate profit margins or your budget then your business plan could also lead to failure. Stick to the figures and be realistic and your plan should hold you in good stead in the turbulent business market.