In addition to "phrase searching," Boolean operators, and truncation, you can also try using wildcard searches.
Like truncation, wildcard searches will expand your results. Wildcard searches allow the database to replace the wildcard symbol with any letters that would make up a real word. It's like a shorthand way of typing every possible word that fits the pattern with OR in between. Not only will this save you time, but it might also give you alternative keywords you hadn't even thought of.
Here's a table to illustrate how some of these symbols (including the truncation asterisk) typically work.
|Symbol||What it does||Sample search||Instead of typing|
|*||replaces zero or more letters at the end of a word
(this is truncation)
|comput*||computer OR computing OR computational OR...|
|#||replaces at most one letter||ne#t||net OR neat OR next OR nest OR...|
|?||replaces only one letter||b?t||bat OR bet OR bit OR bot OR but OR...|
REMEMBER: Some databases may use these symbols differently or may use different symbols, so check the database's help section if you're having problems with wildcards.