Besides just asking if your source is credible, you need to think how it fits into the argument you are making in your research. Credible information that you don't know how to use is not helpful!
A great tool for evaluating how to use a source is the BEAM method.
Check out this graphic on Analyzing Rhetorical Use of Sources: The BEAM Model from Indiana University Libraries!
The BEAM method helps you figure out how to use sources in your argument. Find your sources and evaluate them, organizing them by BEAM categories. One source can fit into multiple categories.
MLA citation: Bizup, Joseph. "BEAM: A Rhetorical Vocabulary for Teaching Research-Based Writing." Rhetoric Review 27.1 (2008). 72-85.