When an author is a professional author (newspaper reporter, etc.) rather than an expert in a field related to your topic, it is important to remember that expertise in writing is not an indication of accuracy. Instead, the reader must examine the author's own research practices.
Did the author interview and quote credible experts? How can we know? Perform a credibility check on those quoted by Googling their name, along with area of reported expertise.
Does the author provide evidence of research conducted. A bibliography is a sure sign of this effort. Be sure to review the bibliography and evaluate the author's choice of sources.
No bibliography? Not all sources (particularly news and web based sources) provide a formal bibliography. Look for other means of citation. Authors will often refer to resources within the text and online, they will often link to the resources themselves. Click on the resources and check them out.
Just as you establish your credibility through your own selection of sources, so does every author. Demand the same scholarly approach of any resource before relying in it.
Remember to look for: