6 Principles of Persuasion

• Reciprocity: people are obliged to give back to others the form of a behavior, gift, or service that they have received first.
• Scarcity: people want more of those things they can have less of.
• Authority: people follow the lead of credible, knowledgeable experts.
• Consistency: People like to be consistent with the things they have previously said or done. Looks for voluntary, active, and public commitments and ideally gets those commitments in writing.
• Liking: People prefer to say yes to those that they like. We like people who are similar to us, we like people who pay us compliments, and we like people who cooperate with us towards mutual goals.
• Consensus: Especially when they are uncertain, people will look to the actions and behaviors of others to determine their own.

This model comes from the book "Influence: The Psychology of Persuasion" by Robert Cialdini.