You've done your search in a database and found a list of articles. Or you have some book titles to consider. You now have to decide whether or not these potential sources help you accomplish your purpose. One way to do that is to see how you might use those sources in your research paper.
The BEAM model below might be helpful. As you examine your results ask yourself, does this source fall into one (or more) of the categories below?
Adapted from Beeghly LIbrary, Heidelberg University: http://libguides.heidelberg.edu/eval/beam#s-lg-box-2260491
Meredith Farkas, Meredith. “Good for What? Teaching Sources for Sustainable Lifelong Information Literacy." Presentation, Association of College and Research Libraries, Portland, OR, March 25-28, 2015. http://www.slideshare.net/meredithfarkas/good-for-what
Rubick. Kate. 2014. "Flashlight: Using Bizup's BEAM to Illuminate the Rhetoric of Research." Presentation at Library Instruction West 2014. http://pdxscholar.library.pdx.edu/liw_portland/Presentations/Material/10/
Rumble, Juliet, Carter. Toni and Noe, Nancy. 2015. "Teaching Students the 'How' and 'Why' of Source Evaluation: Pedagogies that Empower Communities of Learning and Scholarship." Presentation at 2015 LOEX Conference. http://www.loexconference.org/2015/presentations/rumblePresentation.pdf
Woodward, Kristin M. and Ganski, Kate L., “BEAM Lesson Plan” (2013). UWM Libraries Instructional Materials. Paper 1. http://dc.uwm.edu/lib_staff_files/1
BEAM originally developed by Joseph Bizup.
Bizup, Joseph. "BEAM: A Rhetorical Vocabulary for Teaching Research-Based Writing." Rhetoric Review 27, no. 1 (2008): 72-86. doi:10.1080/07350190701738858