Before you search, take a moment to think about what you are looking for. What words are you going to use in your search? This is a step most people skip, but it is something that will help you if you aren't finding the kinds of results you want (or not finding any useful results at all.)
Below is a video from the University of Houston libraries that discusses thinking about synonyms and related concepts to create good search terms (keywords.) They make a really important point here--the way that you might describe something isn't necessarily how someone else might describe it. Keep that in mind when you search, and don't be afraid to try different words and combinations of words.
This video will give you tips about how to tell the difference between a "scholarly" (or "academic" or "peer-reviewed") article and a "popular" article. Scholarly articles have been reviewed by experts, and so the information contained within is often more trustworthy. Often, these are the kinds of materials your professors will want!.