Select the most important 2-4 words 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.
deforestation AND orangutans
Use quotation marks ( " " ) around phrases (two or more words); this tells the database to look for the words right next to each other.
"palm oil" AND deforestation
Use the asterisk (*) to truncate a word; this tells the database to look for all words that have the same base. In the example below, search results would include "governance" and "governing."
"drinking water" AND govern*
Use synonyms and related terms:
"global warming" AND"ice melt"
"global warming" AND glaciers
"global warming" AND "arctic ice"
Look at the number of results.
Too Many: Add keywords or be more specific.
Too Few: Change keywords or make them more broad.