If you know some basic things about your subject, newspaper and magazine archives are really good sources. Most states have free historical newspaper sites (this one is for California: http://cdnc.ucr.edu/cdnc
). And Cornell and the University of Michigan have coop sites titled "Making of America" that have a whole bunch of 19th century American magazines (Harper's, Atlantic, Scribner's, Century). Find Cornell here: http://ebooks.library.cornell.edu/m/moa/browse.html
and UM here: http://quod.lib.umich.edu/m/moajrnl/browse.journals/
. The Library of Congress http://www.loc.gov
has digitized a substantial collection of personal papers, historical photographs, and veterans' reminiscences. LOC also has a newspaper archive (that ties into the state sites). For tips on using these resources you might check out Finding Stuff at http://www.steventrentsmith.blogspot.com
. Many newspaper archives are fee-based (NY Times, London Times, Washington Post). Some let you buy one story at a time, others require a subscription. The same is true for some magazines. Google has a few periodicals - like Life
- here: http://books.google.com
. Good luck and have fun.