"Plans are useless; planning is indispensable," according to Dwight D. Eisenhower, then Commander of the Allied Forces in Europe during WWII. Now, you may be in total agreement with the first part of that statement, but you are really not convinced of the truth of the second part.
American Demographics (adage.com/americandemographics): Just as the title suggests, numerous free reports about consumer demographics in the U.S. nationally and by statistical area.
So this is a very user-friendly method too. The content includes eye-catching graphics which are placed purposefully to magnetize the attention of viewers whereas good content is written to complement the graphics to make website interactive. Maintenance of a website template is so easy. Normal changes in the website can be done without any problem and without even changing layout of your website.
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: