While Google's algorithm often does a great job of figuring out what you're after no matter what you've typed, you can make it do certain things that will help your search.
Many of the Search Tips in this guide can be adapted for use in Google. Consider the following tricks:
If you compare a Google search to a search in a library database, you'll most likely find a lot more sources. You'll also find sources with all sorts of purposes, from respected news sources to content farms. So look closely at what you've found before considering it as a reliable source for your research.