You send people signals all day, without paying attention to them. The way you move your eyes, the way you shake a hand and so on. There are things you can do to send subconscious signals using body language that make people like you better, or at least give you the benefit of the doubt. Whenever I discuss techniques like these there are always one or two people who feel uncomfortable with ‘influencing’ someone with psychological tricks.
Manipulation is not negative
Influencing is changing someone’s behavior or mind