Use the CRAP Test to evaluate sources you find:
Currency
Reliability
Authority
Purpose/Point of View
This very good video from CSUCB's Pfau Library will help explain the difference between scholarly and popular articles and how to tell which you are looking at.
*Pro Tip: Just as with your own writing, audience is critical to evaluation. When a noted expert is authoring a newspaper or magazine article, they are anticipating a popular audience and write accordingly. So even though you may have the most brilliant thinker of all-time on your topic writing a piece, it is only "scholarly" if their audience is other scholars.