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.
Another point of contention is how optimistic you should make your business plan. The problem with making over-optimistic predictions and plans is that these plans could well go wrong. Unforeseen circumstances can always put a spanner in the works. Therefore, it's wise to err on the side of caution when it comes to devising your business plan. Indeed, it's wise to predict conservatively and prudently when it comes to assessing the possibilities of future targets, sales and profits. A worst-case scenario will always prove to be less of a shock than one that raises expectations too high.