If you are not familiar with BOOLEAN OPERATORS and how they work, spend a few minutes viewing a tutorial on boolean operators. Google, Bing, all of the MU Libraries' databases and catalogs use boolean operators. You will not be using your time effectively unless you know how Boolean operators work.
The tips on Narrowing a Topic can help you focus your topic and save you time.
The tips on Broadening a Topic are useful if you are trying to do a comprehensive search.