Truncation- Use an asterisk(*) to truncate words so you can get results that have the root of a word. For instance, if I'm interested in researching child psychology, I may truncate child* to get results like children and childhood.
Quotation Marks- Use quotation marks to help get keywords in a specific order to show up in your search results. For example: A Raisin in the Sun vs. "A Raisin in the Sun"
Consider using OR to connect similar search ideas. For instance, if you're searching teenagers, you may also consider adolescents. A search phrase using this would like this: teenagers OR Adolescents
Hint: You can find the OR option in the drop down connecting search boxes in most databases.