...It is possible to see excellence as, essentially, quality in abundance. That is, "excellence" would refer, in effect, to high scores for "quality." This notion, which seems to underlie Gladney's work, seems entirely appropriate to his and others' studies of how excellence is measured within a publication or organization. But excellence in individual works of journalism is another matter - both because many of the criteria do not apply (e.g., the amount of wire copy) and because some of the others (e.g., accuracy) would be seen by most journalists not as criteria of excellence for particular works but as bare minimum requirements.
In 2001, U.S. authors Kovach and Rosenstiel, reporting on the work of the Committee of Concerned Journalists, made a start on the road toward establishing consensus standards of excellence by listing, explaining, and illustrating ten "principles that journalists agree on." The first is a statement of the purpose of journalism ("to provide people with the information they need to be free and self-governing"), and the other nine are statements about what is needed for journalists to achieve this goal. Those nine statements address journalists' obligations of truthfulness and verification, their duties of loyalty to citizens and independence from those they cover, their role as monitors of power and providers of "a forum for public criticism and compromise," the need for journalism to be interesting, relevant, comprehensive, and proportional, and the need for journalists to exercise freedom of conscience (Kovach & Rosenstiel, 2001). While these "elements of journalism" do not masquerade as agreed standards of excellence, they have reinvigorated a discussion on these standards and, generally, been well received by practising journalists and scholars alike.
A quality source has first hand information. A witness or participant to an event. Do a quick search of the person before posting to make sure they are not an interested party attempting to sway the discourse. Make sure they don't have a motive to paint they story.
Also try to find multiple sources so you can reinforce the story. You will find if you do a quoted excerpt search that in most cases the multiple stories you see in news sites nation wide are simply cut and pasted across the AP or other wire service news chain. This can make finding the original story difficult, but not impossible, use the time parameters on the search engine to clear out the news service filling it up as those stories are usually late in the game.
If you are using a textual source like a link or reference to a hard copy printed work looking at the quality of the writing indicates the source is more reliable. I do find exceptions to this. When something is translated into English especially by the writer themselves the quality of the writing is most likely going to be poor, you should not discount their information if this is the case. To add the social stratification in our poorest urban areas means that the language used in these enclaves is also in need of translation, please don't discount the vernacular. One more exception is Anarchists, they rarely use conventional writing styles on purpose and this is seen as a lack of literacy, this too must be taken into account when considering source quality based on writing ability.
When looking at a webpage for news follow their links to their source. Reassess this source as well to ensure validity. If there are no links then do a key word search and if that does not direct you to their source or a reliable source do a search of a quoted excerpt from the story you are trying to verify. That sometimes provides a source of that text.
Looking at the date of the information is important. Not just the date of the post. Make sure you search any story on a search engine if that story is not from an established journalistic site.
Recommended reading:
Finding and assessing sources
A study on the changes the internet has made to journalism