Internet Public Library - The Census Data and Demographics (ipl.org)/: An especially useful site that has links to information about countries other than the U.S.
At this point, you may be tempted to skip writing a business plan altogether, viewing it as an unnecessary exercise in jumping-through-the-hoops, suggested by some old business professor who probably never held down a "real" job anyway.
If you know all of these except for Marketing, say, then this is where you will need to invest some time and effort. You can find a wealth of information by utilizing the traditional data sources such as chambers of commerce, major cities' websites, trade associations, the US Census Bureau, trade journals, magazine and online articles and advertising, etc. Performing keyword searches on Google, or Ask will bring up websites to check out. Following are some places to start:
Risk Assessment - What weaknesses are inherent in this venture? What vulnerabilities face this type of venture? What impact will these have? What new technologies may affect this venture over the next 1 to 3 years? What contingency plans are in place? What level of liability insurance is required? What does it cost? Who is the carrier? Possible Data Sources: trade associations; trade journals; Service Corps of Retired Executives (SCORE); industry salespeople; customers; focus groups.