Be truthful and correct. Quoting advocacy groups’ studies or polls does little to help your argument. If you quote an authority, know the person's views and speciality intimately. Avoid referencing trendy intellectuals; name dropping of this kind will turn off a portion of your audience. In most cases, you are not expected to cite your sources, but you should be certain your information is clear and correct before you submit it. Otherwise, readers and editors will question the validity of your entire piece.
According to the Americans Moralistic Society, 85 percent of Americans believe that our "moral values" are getting worse.
According to the annual Gallup Values and Beliefs Poll from May 2011, 69 percent of Americans believe that our "moral values" are getting worse.
Regardless if the information in the first example is correct or not, critical readers will immediately be turned off by the name of the source. Find a study from a reputable group instead. Even if the information in that study is not as powerful, readers are more likely to trust information from what they perceive to be a more objective source. No group is universally accepted as a definitive source, so consider the cost–benefit ratio of using the findings before you include them.
Appealing to authority
Love is a complex emotion. Friedrich Nietzsche once stated "There is always some madness in love. But there is always, also, some method in madness."
Using quotes from authoritative subjects is very risky. Very often, quotes are misattributed to various authority figures. Before using a quote, ensure that the person actually said it.
Most politicians are intelligent, but they have no business creating science curricula. Richard Feynman once said "In this age of specialization, men who thoroughly know one field are often incompetent to discuss another."
Though the quote from Nietzche is accurate and correctly attributed, Nietzsche is not regarded as an authority on love. Quoting an inappropriate authority, even correctly, can demean your own cause. The second quote may not regard a subject in which Richard Feynman was considered an expert (politics), but it ties in well with his own field (physics).
Noam Chomsky once complained of "the uniformity and obedience of the media, which any dictator would admire."
Chomsky is an expert in this field, but his name will generate negative connotations in many of your readers.
Unclear or incorrect information
Sarah Palin quit her job as governor because of ethics violations and associated with the felon Ted Stevens.
Sarah Palin quit her job amid a series of ethics investigations.
Though Palin did quit during a series of ethics investigations, it is unclear whether this was her primary motivation for leaving office. The second example hints at the possibility of a correlation, but does not state it directly. Ted Stevens may have been convicted of a felony, but a judge has since overturned his conviction and thus he should not be referred to as a felon. The second example removes this clause entirely.