Newspapers vary in quality; The tabloids at the supermarket check out are sensational, articles in the Globe or the Washington Post are usually well researched but editors and columnists write opinions.
Authors. Do you know anything about the author? (A web page created by a 5th grade class about Ancient Greece may not be the most reliable source. A book may have been self-published.)
Is the material dated? A book or web page about the American Civil war need not be updated frequently. Today's news about a current civil war may be contradicted tomorrow.
Is there a bibliography or are there links to other sources? These may corroborate arguments or show bias.
Can you detect bias or prejudice? Newspaper editors and columnists are often known for their stance on some issues. Beware of immoderate language (never, worst, unique) unless evidence is provided to support it.
Is a product or a point of view being promoted? Magazine advertisements often look like articles. Contrary facts may be left out.
Does the author or an associate stand to benefit from publishing
the information at this time? Research funded by drug
companies sometimes fails to identify adverse side effects.
This should be accurate information:
e.g. Department of Energy at http://www.energy.gov/
but not necessarily impartial.
.org means a non profit organization.
This could be great:
e.g. PBS at http://www.pbs.org/
But may have an agenda:
e.g. The NRA at http://www.nra.org
Creationism.org at http://www.creationism.org/
National Abortion Federation: Voice of Abortion Providers at http://www.prochoice.org/
National Right to Life: Where Does Life Begin at http://www.nrlc.org/abortion/wdlb/wdlb.html
e.g. University of Massachusetts at http://www.massachusetts.edu/
BUT, you should know that a tilde (~) indicates an individual's personal web page: it may belong to a professor or a student!