Select the most important 2-3 ideas related to your topic. Put the word AND between each new word or idea; this tells the database to look for resources with ALL your terms.
fire science AND prevention
Use quotation marks ( " " ) around phrases (two or more words); this tells the database to look for the words in a specific order.
"fire science" AND prevention
Use an asterisk ( * ) to find multiple versions of one word. Using prevent* as a search term will include results that refer to prevent, prevents, prevented, preventing, etc.