How can you effectively convince someone about something?
An effective way to convince someone is to use Ethos, Pathos, Logos.
They were Aristotle's concepts of Rhetoric. It is used in speeches, writings, and in real-life situations by people informed of the 3 concepts.
Ethos: Using your credibility or character to convince others. We are more convinced if the character we portray is wise, respectful, likeable, etc. We are more willing to listen to someone that we believe has great character rather than listen to words coming out of a disrespectful, conceited, etc. kind of person.
Pathos: Using emotional appeals to sway others towards your idea. We can all agree that being able to connect or relate to someone is very effective; we tend to like them more. We humans can be easy persuade through sympathetic emotions, or just knowing that someone understands us. Show emotion by discussing how you feel, an emotional experience, or even an emotional metaphor.
Logos: Logos is probably the most critical one, that can be used in any situations. Logos is simply "logic". Logic can persuade anyone, if done right. Use reasonable explanations, research results, data, inferences, reasoning, etc. to back up your idea. In order to persuade (or even trick) someone, use details and logic. Ask yourself, "What logically explanations can back up my opinion?"
For example, Martin Luther King Jr. used the 3 rhetoric concepts in his famous "I Have a Dream" speech in 1963. The title of the speech, "I have a dream" is considered by some as Pathos, because having a dream is relate-able to every human beings. We all desire and strive for certain goals. Also, President John F. Kennedy was known for his excellent speaking skills; appealing to masses using all 3 rhetoric concepts. Part of his success in the presidential election was because of his ability to bring character, emotion, and logic to his words.