When you first enter PubMed, you can start entering search terms into the Basic Search box. To use the basic search box effectively, you will need to build a search strategy using operators (AND, OR, NOT) and putting parentheses to denote topics.
BROADEN: Use * after 4 characters to get unlimited amounts of root endings (example chil* returns children, chilled, chile, etc).
NARROW: Use Search tags like [TIAB] to look only in the Title and Abstract field.
DISPLAY OPTIONS: Use the Abstract format to quickly read over the abstracts and change the number of results you want to see at once.