Your topic will have limits.
You need to work out what words may limit your search, as this will help you form an effective strategy to find information.
The most common limits are:
Your research may be limited by demographics to a portion of the population (e.g. age group, gender, education), or by Industry (e.g. media, construction, aged care). You may need a particular type of information such as statistics or product reviews.
You may need to find information that has been peer reviewed. At USC, you are often required to find scholarly or academic sources.