In general, these tips work for most databases. Always check out the "Help" menus to see all of the helpful search tips to give you the most accurate results.
AND- Narrows down the search
OR- Broadens your search
NOT- Excludes terms from results (use with caution)
Truncation * - Allows you to search for variations on a term
Wildcard ? - Allows you to search for alternate spellings within words
Tilde ~ - Proximity search which returns results within a specified range of words
Stemming # - Finds variations of a word,
Quotes " "- Results have the exact phrase as entered
Parenthesis ( )- Allows you to combine many or these search strategies in a single search box
There are many more great tips in database help screens.