#3 Find out what other sites say about this site. Mike Caulfield refers to this as "reading laterally".
These two sites are helpful in finding out more about news sources.
Media Bias Fact Check (MBFC News) At the Search page, type in a news publication, e.g. CNN, under Dedicated Media Search. MBFC provide information on both bias (least biased, left-center bias, right-center bias, left bias, right bias, and extreme) and level of factual reporting. to learn more about its reporting and bias. MBFC explains how it determines bias in its Methodology section.
AllSides Select Media Bias > Media Bias Ratings to search for a news source. Each news source classifies news sources into categories: center, lean left bias, lean right bias, left bias and right bias. AllSides determines its bias ratings through blind surveys, third party data, and community feedback. AllSides also features news on specific issues from the center, right, and left.