Background research paves the way for productive archival research.  Use it to get an overview of your topic, to zero in on the details you need to find primary sources, and to help put archival materials in context.

• Gather the basic facts about your topic and familiarize yourself with the major themes and concerns of the day. 
• Read books and articles for more in-depth coverage of the people, organizations, and events that are central to your research project.
• Tertiary (Reference) and secondary sources will help you decipher documents in archival collections. Letters in a manuscript collection exchanged between people who knew each other long ago may mention other people, events, ideas, and opinions, but they probably won't explicitly define them. Reference sources will come to the rescue.
• Take a close look at the footnotes, bibliographies, and acknowledgements in tertiary (reference) and secondary sources.  They are gold mines for identifying primary sources and finding out which libraries or private collections hold them. 
• Keep a running list of the names (people and organizations), dates, keywords, subjects, themes, events, and places that come up in your research.  These will be your access points for finding primary sources. 
• Knowing key names will enable you to recognize relevant sources when you encounter them.
• Knowing key dates will enable you to navigate manuscript collections arranged in chronological order.
• Background research will also help you position your own argument within the scholarly conversation.  
• You can also use background sources to come up with a topic and for help developing your research question.

Source: Mina Rees Library Archival Research

Dissertations are gold mines. They contain original research and can lead you to difficult-to-find primary sources that their authors have tracked down. 

You might want to start with MIT dissertations and theses through Dspace in case related research on your topic was done by MIT alumni. An additional resource to search is the Proquest's Dissertation and Theses Global database. Don't forget to mine the footnotes and bibliographies for related and valuable primary and secondary source leads.   

• For the best results, be flexible when you search. Try different combinations of search terms.
• When searching on personal names, try variant spellings, leave off first names, search whole names in quotes, and try last name, first name.
• Search for people and organizations as “subject,” “author/creator,” and “keyword.”
• Search on older terms and spellings in older sources. For example, if you were researching the early history of automobiles in digitized newspapers, you’d likely have better luck using the term “horseless carriages” than “cars” or “automobiles” because that was the term used between 1895 and 1910.
• Browse the “categories” section of the Oxford English Dictionary online to explore disused, archaic, and regional terms.
• Search for materials in multiple places. Try WorldCat, ArchiveGrid and the websites, catalogs, and databases of the libraries likely holding sources on your topic.
• Use keywords such as sources, archives, correspondence, diaries, interviews, narratives, or memoirs to find primary sources in a library catalog.

Seek out newspapers contemporary to your research topic and read them to get a sense of the time and place you are studying. 

• Historical newspapers are great primary sources that can help you understand how a subject was viewed and understood at the time. They also fill in the record on people and topics that may not turn up in archival collections.
• Don't forget the alternative press!  Many ideas that are accepted today were considered radical when they were first introduced. You'll find coverage of new or progressive ideas in radical publications before it appears in the mainstream media.  And you'll also hear the voices of marginalized people and organizations in the radical, underground, and independent media.

Check out the Historical Newspapers Guide for tips on finding newspapers and MIT Libraries subscriptions. 

Source: Mina Rees Library Archival Research