Archivists typically, though not exclusively, possess graduate degrees in either history or library science. A number of colleges and universities offer courses in archival administration, usually within their graduate history or library science offerings, and some employers will look for such courses in the background of candidates. The SAA's Employment Bulletin is a good place to get a feel for who hires archivists and what these employers look for.
Most archival institutions welcome volunteers.
The National Archives and Records Administration offers a wide range of voluntary student internships at our facilities around the country. On the other hand, you may wish to contact local and state governments, college and university libraries, and historical societies about opportunities near you. In either case, service in an archival institution either as a volunteer or an employee would be a good way to learn more about the field. For a discussion of archival careers, see the Archivists and Curators entry in the U.S. Department of Labor's Occupational Outlook Handbook .