Learn about Subject Specific Databases
Google and Google Scholar are great, but for graduate work you will have to become a better researcher.
The Library subscribes to hundreds of journal databases as well as online encyclopedias and citation indexes. You need to become familiar with the major indexes in you field and learn how to search them efficiently.
Learn which scholars are important in your field
How do you learn who is important in your field? In addition to asking your professors and fellow students,
if you are in the sciences or social sciences you can look at citation indexes like
You can also look at Journal Citation Reports to see which journals have the most cited articles in your field.
For books, you might go to Amazon and look at customer reviews.
These reviews will often lead you to the core books in your field.
You might also search USC Library Search for books. Their system will give you reviews from Choice and Publishers Weekly (if available).