There are many ways to express that, more so when we dig deeper into the social levels, backgrounds, where one lives, if we want a retro word, etc.
One way that is almost all-encompassing is "cool
", it was always a very sought-after thing with teens to be popular, noticed and worth to be emulated. This is what cool means in "Everybody Hates Being Cool" (Todo mundo odeia ser descolado), episode 19 season 3 of said sitcom.http://www.theiscream.com/what-the-fuck ... l-anymore/
Branching the word out, we could then say that it means to be "hipster
" (a bit outdated word, but still used) that in turn could be a number of things: one that is in the know, one that knows what´s going on, etc.
Hipster means young person who is trendy, stylish, or progressive in an unconventional way; someone who is hip.
There are other ways mean it: one that is a smart cookie/sharp/clever/in the know/on the ball/sharp cookie/to be the man. All said in a context meant to be cumplimentary/flattering.
Also stylish, trendy, fashionable, jazzy, ritzy
, generally used by people into fashion, or when appreciating the clothes others are using.Savvy
is one word sometimes used to mean the person is "descolada" (in the know) on some subject, an insider or well-informed person (or even seasoned), etc. As in "he is a savvy investor/he is a savvy business person/He is a savvy problem-solver and an expert in master planning."
And there are other words and ways to express it. That is just my two cents.