1. Write your research question, and then select only the main keywords (in bold in the example):
Is there an association between bone density and corticosteroids?
2. Think of synonyms for your keywords
Quotation Marks " "
A more complex search is NESTING.
With nesting, you search groups of terms by using the Boolean and parenthesis
Ex.: (teenagers OR minors) AND (drinking OR alcohol)
will retrieve: teenagers and drinking, teenagers and alcohol, minors and drinking, minors and alcohol