Boolean logic - see the Grumpy Cat visual for an example: use AND, OR, NOT (sometimes AND NOT) to connect two or more search terms:
Phrases in Quotes - most databases and web search engines allow you to search for exact phrases by placing them in quotes:
Truncation - the library catalog and most databases use special characters to make searching easier in certain situations. Check the help screens in the catalog or database you are using to see what the special characters are for that resource.
Nesting - use parentheses to sort out the elements of a more complex Boolean search phrase, especially when you may want to search for more than one related term for one element of your phrase: