You read rooms. You catch the pause before someone changes the subject, the sentence that came out slightly too smooth. You usually cannot say where the impression came from, only that it has never been far wrong.
Because you cannot show your working, you keep a lot of it to yourself. That has made you seem private, sometimes further away than you are. People know less about you than they think they do, and you are mostly fine with that.
The thing worth practising is saying the impression out loud before it is fully formed. You have been right often enough to earn the benefit of the doubt.