People say yes to those they like. This is why all my sales are done through in-person meeting. Each meeting, I am mindful of my language and jokes. It should never be offensive. The easiest trick? Encourage the person to talk about themselves.
We feel obligated to return favors. This aligns with Robert Greene's law on Power - "Despise the Free Lunch". Something free always have a hidden obligation. This is why good coffee at car dealerships.
Social proof runs everything. We buy things by reading reviews or customer testimonials. If the item is cheap, I might take a risk. Otherwise, I would read the reviews before deciding.
Authority makes us compliance machines. I grow up respecting anyone in uniform. I vividly remembering toothpaste advertisement where the actor wearing a white coat claiming to be a dentist. When I meet with customers, I make sure I am properly attired for the occasion.
Scarcity creates instant desire. "Limited time offer," "only 2 left in stock," I am a sucker for suck tricks. Luxury watch company would limit the supply of their watches creating an artificial shortage, thus making their watches more desirable in the market.
Commitment and consistency trap us. This is related to point 1. When we choose to like someone or committed to someone, we have created an identity within ourselves and choose to stay that way. I wonder why people still cheat in relationship?
Reciprocation works even when you do not want the initial favor. This is related to Point 2. Someone does something "nice" for me and I feel obligated to return it. Occasionally, I feel that way. This is why I refuse to attend any "free" lunch or "free" seminars.
Final Thoughts Such influence tactics are all around us. It is important to pick signs that we are being influenced. Also learn to use such methods in our life, career and business.