Accuracy: is information verifiable in other sources? Are citations/bibliography included? Is source peer-reviewed?
Agenda: Is the information sponsored by an industry/organization? Is the author clearly affiliated with a particular school of thought?
Audience: For whom is the source written? How does this audience relate to the audience for whom you are writing?
Authority: Who is the author or creator of this source? What are their credentials? Are they experts on the topic?
Currency: How old is the information? Is it still relevant/applicable?
Relevance: Is the information in the source relevant to your topic/project?