Is the website it is on trustworthy?
If someone shares an article on a news outlet you haven't heard of yet, it might be useful to take a look at the frontpage. If all the articles appear to have a very obvious one-sided political slant or even go into conspiracy theory territory, you might be reading a fake-news or propaganda website.
Or it might even not be a news website at all, but a think tank or a political organization which published something which might read like a serious news article if seen out-of-context but is actually part of their agenda.
Is the headline phrased as a question?
If so, then the answer to that question is usually "maybe, but probably not". If the news outlet would be sure about something, they would phrase the headline as a statement. When a news headline is phrased as a question, then that usually means that the news outline is reporting on a rumor or makes an educated guess, but they have nothing to prove it.
Is it news or is it opinion?
Most news outlets publish two kinds of articles: "News" and "Opinion pieces". The first should be objective. The latter represent the personal opinion of a staff member or freelancer and will make an argument for that opinion to be right. Learn to tell the difference between these two. The first might be a reliable source, but the latter is not necessarily trustworthy because it will only mention the facts which support the author's opinion.
Who is the source?
A good news article should mention how the journalist learned about the information. The source of the information might tell you how reliable it is.
- If the source is a politician or political organization, keep in mind that the source has a political agenda and will only publish what furthers that agenda. Also, politicians are not universal experts on everything. If a politician talks about things they are not experts on, like psychology, civil engineering, warfare or meteorology, take what they say with a grain of salt.
- If the source is "scientists" or "a study", verify if the study actually says that. Journalists love to blow scientific findings out of proportion and tend to interpret conclusions into scientific publications which go far further than what the publication actually says. Also, keep in mind that the quality of scientific publications vary a lot. There is a lot of bad science which gets published because the author is under pressure to publish some results. It is often not easy for laypeople to tell good science apart from bad science. But a common sniff-test of bad science is a small sample size, lack of a control group, a sample which is not representative or results which are not really statistically significant. If you want to do more "research into research" see what other scientists in the field think about this. If they point out that the study conflicts with the findings of other studies which are based on far better data or if they mention that the author might not be qualified in that field, then the story might not be as reliable as it seems. But if other scientists are just as excited about the finding as the journalist, then there might be merit to it.
- If the source is "an expert" or "a witness", remember that humans are fallible. Experts might not actually be as knowledgeable as they pretend to be. Witnesses might remember things incorrectly or lie.
- If the source is unnamed, you should probably not pay much attention to this at all.
Is the information corroborated by other news outlets?
Be careful when there is only a single news outlet which reports something. When a news is really as big as they claim, others will also report on it. If you find other news reports about something, make sure that they actually have their own sources and are not just repeating what another news outlet reported.