Investigate the Source. Look at the name of the site. What do other sites have to say about the site in question?
Read About the Source. Most reputable sites have an "About Us" page. Take the time to read it. Check for grammar and spelling errors.
Pay Attention to the URL. A number of sites use URLs that attempt to appear like well known news organizations. But upon closer examination, you can see slight anomalies. Search for the real site and see if the site you are investigating comes up.
Look at the Page Itself. Does it look like the page of a professional, reputable, news organization? Is other news being covered? Is there a large, diverse history of additional stories covered by the site?
Does the Site "Cherry-pick" Facts? Does the site ignore facts that don't support their favored position? Reputable news sites present reliable information on multiple perspectives.
Fact v. Opinion. Does the site make a clear distinction between stories based on verifiable fact and opinion-based editorials?
Are there a lot of Pop-up and Banner Ads? If there are, this could indicate that the site is really just a home for clickbait.
Who is Providing the Information and Why? Who is responsible for the site? Why does the site exist? Is it clickbait to provide income for the site?
Verify. Are sources for the story listed in the article? Can you find other, reputable sources covering the story?
Is the Story Designed to Excite You? Journalists usually do not make a call to action when writing an article. In a professional news story you are given the facts.