The key to success in any interview is preparation. The hiring manager has taken the time to read your resume and even possible research you. The least you can do is show similar respect by researching the company you’ll be interviewing with. If you have time, it is also wise to research the hiring manager as well.
Employer information from the library: There are many ways to research a hiring company and hiring managers. Your local librarian can help out, most likely they will be able to pull up demographics on the employer and possibly even a list of recent events or press releases.
Employer information from the employer: The hiring company will likely have a stack of brochures or at least a company prospectus. All you have to do is call and ask. If you are uncomfortable calling the hiring manager or HR department, you could try asking the receptionist or ask for someone in the sales department.
Employer information online: The fastest and easiest way to find information on hiring managers or a potential employer is linkedIn. The company tool on linked in contains a great deal about most companies. In some cases it lists number of employees, annual revenue, and even office locations.
The more you know about a potential employer, the better your conversations will be. Just remember to check your sources and take notes.