Finding information on small, private companies often requires checking multiple databases and directories. If the company is very small or new, you may not find much information at all.
Web Sites: First try locating the company's web site as they sometimes offer some good info.
Newspaper & Trade Journal Articles: The most informative sources for small, hard-to-find companies can be articles in newspapers, magazines and trade journals so try:
Initial Public Offerings - Growing companies may be on their way to going public which would include filing statements with the SEC before actually being listed. Check EDGAR, below to see if your company has filed.