Select the most important 2-3 terms related to your topic. Put the word AND between each new term; this tells the database to look for resources with ALL your terms.
smallpox AND washington AND army
Use quotation marks ( " " ) around phrases (two or more words); this tells the database to look for the words in that specific order.
"continental army" AND smallpox
Use an asterisk ( * ) to find multiple endings of one word. Using adopt* as a search term will include results that refer to adopt, adopts, adopted, adopting, and adoption.