The mirror technique.

People tend to trust those who look like them. The following logic works here: familiar means understandable, understandable means trustworthy. Look closely at the interlocutor, listen to his intonations, pay attention to the manner of speaking and gesticulating. This rule also applies to nonverbal communication. Your opponent jokes — joke in response, tells something confidentially — listen with participation, gestures — repeat his gestures. This also works with a large audience, just study your listeners as much as possible before the performance