Not all sources will be appropriate for your project. Even if they contain information you find interesting or exciting, if they are not suited for the kind of research you are doing, they will undermine the integrity and authority of your project.
Scholarly vs. Popular Sources
With books and articles especially, it is important you know the difference between scholarly and popular articles. Since you are in a university library, most of the materials you examine will be scholarly, but you should still be able to tell the difference.
...are written for a specialized audience, including faculty, researchers, scholars, and advanced students.
...often employ technical language and terms and are longer.
...are more thoroughly supported by a bibliography and/or source citations.
...are generally reviewed by peers before publication
...aim at a general, non-specialist audience.
...rarely use technical terms and are shorter.
...often lack a bibliography or more extensive source citations
...may be reviewed by an editor or fact-checker (depending on the publisher), but are not usually peer-reviewed.
Generally, you want to make sure your sources are scholarly, not popular. One exception is if your project is about popular sources in some way (e.g. popular portrayals of African-American men in U.S. magazines during the 1960s).
So you've found a source that's relevant to your project. What now?
First off, read it!
Keep in mind you don't necessarily need to read an entire book to get what you need out of it. Be sure to use the table of contents and index as ways of finding the material that is relevant to you.
As you read, you should be thinking critically about what you're reading. Here are a few things to keep in mind:
Checklist for Evaluating Research Sources
Is the authority in this material clear and legitimate? Is the writer qualified?
Can the factual information be verified by legitimate authority? Can one opinion be verified against another?
Is the material objective and free of advertising, bias, and hidden agendas? Is the language impartial? Is the statistical evidence credible?
Is the material updated frequently to ensure currency? Does the material reflect the most up-to-date research?
Is the material complete, partial, or out of context? If the material is out of context, is there a path to find the source? If the material is out of copyright, has it been updated to make it more current?