Knowing the 4-digit SIC and 6-digit NAICS code for your industry will help you find information. The U.S. Bureau of the Census has a website that will help you identify the best number for your business. If you need to convert SIC to NAICS or vice versa, the bureau provides a concordance.
Trade associations collect information on their industry. Sometimes they will provide free data, but other times you may have to contact the association directly to see what they have. Check out the website and look for links labeled "Research," "Media," or "Statistics." You can find trade groups listed in the sources listed above and also use do an internet search (but review the results carefully).
Trade journals can provide valuable data for the entrepreneur. Trade associations often publish them and may provide access via their website. You'll also find trade magazines listed in the "Industry References" section of Industry Surveys (NetAdvantage). Contact us via the library homepage to see if the Libraries provide access.
Sample associations: Sustainable Apparel Association, Home Furnishings Association, National Retail Federation