Below are some very general search strategy tips that should work on the majority of databases that you will encounter. They are simple ways to better focus your search and will help you retrieve more relevant results.
I say 'should" because, unfortunately, they won't work exactly this way in every single database out there. Luckily databases will have a Help link that will tell you how they specifically use these operators and modifiers. If you continue to run into trouble, librarians are of course happy to help; the earlier you ask for help the better we can assist you.
AND is going to narrow your search. Asking the database to retrieve results that contain all terms.
OR is going to broaden your search. Asking the database to retrieve results that contain either term
NOT is going to narrow your search. Asking the database to retrieve results that contain only the first term.
Modifiers help focus your search even further.
Quotations ask the database to search for an exact phrase instead of two separate terms (ex. "gestational diabetes" instead of gestational AND diabetes)
Asterisks ask the database to search for alternative word endings (ex. color* = coloring, colorblind, colorings, colorization, etc.)
Parentheses force the database to search terms in a specific order; terms within parentheses are read first then terms outside the parentheses are read next.