Use library books, databases for data & articles, and websites to find these:
What age are your best customers?
What are the Business Demographics at your place of business?
What is happening to other businesses in your industry?
How many businesses are providing the same services or products you will within a 5 mile radious?
Do most of your customers purshases services and products online or not?
Where is the best place to advertise?
What are the industry averages for your business?
How has the past economic crises affected your industry?
How has the past economic crises affected your customers?
Does the city, county or state have any information about new building in your area?
Note: Also Use the Web Sites Tab above.
American marketplace: Demographics and spending patterns (2009) by 
Blackwell encyclopedia of management
Business statistics of the United States
Community sourcebook of county demographics
Handbook of U.S. labor statistics
Kiss, bow, or shake hands : Europe : how to do business in 25 European countries
Kiss, bow, or shake hands : the bestselling guide to doing business in more than 60 countries
Society at a glance 2009
The who, what, and where of America: Understanding the American Community
What no one ever tells you about franchising