Answer:
You are in a <em>prime </em>position to change a person's opinion, by following the ethos, pathos, logos rule.
People generally fall into one of the 3 categories:
Ethos: If you are credible, or you can be trusted as you have said the truth numerous times in previous occassions, your words can bear weight in allowing others to believe what you say. As of the opposite, you can have a weaker ethos if what you say does not hold up to what you give the receiver's expectations.
Pathos: If you are likely to appeal to the emotions, then it falls under the pathos category. For example, ads which call for donations as well as first-world countries to stop wasting food may use pictures & videos of the tragedies that occur in 3rd world countries, and may appeal not only for monetary help to help feed the poor, but also to wake up 1st world occupants that their food is vital in other places, and not to waste the precious resources.
Logos: The use of logic, generally factual statements (statements that can be proven and are typically agreed on by a large percentage of humans). Statistical data, history, and many others can be used under this category to help with one's argument as well as disproving another's claim.
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