To search for specific phrases, enclose them in quotation marks. The database will search for those words together in that order.
Truncate a word in order to search for different forms of the same word. Many databases use the asterisk * as the truncation symbol.
Add the truncation symbol to the word screen* to search for screen, screens, screening, etc.
You do have to be careful with truncation. If you add the truncation symbol to the word minor*, the database will search for minor, minors, minority, minorities, etc.
Join together search terms in a logical manner.
AND - narrows searches, used to join dissimilar terms
OR - broadens searches, used to join similar terms
"major depression" AND "primary care"
screen* OR feedback
(screen* OR feedback)