Choose historically appropriate keywords. For example, use "Great War" instead of "World War I" to locate documents discussing the war during and just after it occurred. You may also consider different terms that might have been used to describe the same event from opposing sides or perspectives. 

Search for names. Search for the name of a particular film, art piece, piece of literature, etc. Searching for the names of particular people or places can also be effective, but consider how the names might be presented (last name only, or as part of a title; maiden name or married name) and how country and city names have changed over time. For common last names, you may need to add another term (ex. Kurosawa AND director; Kurosawa AND film) 

Use date limiters. When searching newspapers, date limiters can help increase the relevancy of your results.