Who is the author of the information? What are his credentials? Does he have expertise?
1. Look for a biography/list of credentials of the author. You might find it on the webpage, or under the "About Us" section.
2. Google the author's name: Look to see what else he has published. Is it in the same field? Are the sites he has published credible?
An example of a professional overstepping his authority
Dr. Oz,a well-known TV celebrity and cardiothoraicic surgeon, announced in September 2011 that certain brands of apple juice could be detrimental to kids' health due to unacceptably high levels of arsenic in the juice. (see more information here)
However, the FDA's response to Dr. Oz was that his findings were inconclusive, because he failed to distinguish between inorganic (poisonous) and organic (innocuous) arsenic. Essentially, Dr. Oz (or his people) failed to run the tests properly- because this was not their area of expertise.
In fact, Dr. Besser (an expert withABC News,and a former CDC executive with the Centers for Disease Control) refuted Dr. Oz' findings. (link no longer available)
Perhaps Dr. Oz would do better to speak more about cardiovascular issues, rather than nutrition and research, neither of which he has experience in.
What do you think?