Whether you're looking at a web site, a book, a report, or an article, evaluating a potential source pretty much comes down to CRAAP: Currency, Relevance, Accuracy, Authority, and Purpose.
Currency: Is the information up to date? If not, does that matter in this context?
Relevance: Is this something that would be useful for your research (don't just depend on the title/headline). Is the audience level that it was written for appropriate for your use?
Accuracy: What is the source(s) for the information being provided? Is there credible evidence to support the conclusions? If this is a published article, has it gone through peer-review? If a book, is it published by an university press or other credible publisher?
Authority: What are the author's qualifications for writing on this topic?
Purpose: Is there a discernable purpose for this information to be shared? Is it meant to share knowledge? To inform? To persuade? To incite? Are there discernable biases?