How we change what others think, feel, believe and do
When we consider a person good (or bad) in one category, we are likely to make a similar evaluation in other categories.
It is as if we cannot easily separate categories. It may also be connected with dissonance avoidance, as making them good at one thing and bad at another would make an overall evaluation (which we do anyway) difficult.
Edward Thorndike found, in the 1920s, that when army officers were asked to rate their charges in terms of intelligence, physique, leadership and character, there was a high cross-correlation.
Just because I dress like a rock star, it does not mean I can sing, dance or play the guitar (come to think of it, the same is true of some real rock stars!).
Show how you are good at something, even somewhere relatively unimportant, and then talk about something else where the other person can infer you are equally good.
And the big