That is a damn good question, and to be honest, we cant really know, we just don't have the sources for other Polies that we do for Athens , and those that we do(EG Sparta) can be very problematic. However there are a few examples I would raise to you of how some Greek states differed massively from Athens.

Woman in Athens are often thought to have been treated poorly(huge debate on this i wont bore you with) but look at a place called Gortyn and its surviving law codes to see an entirely different legal status of Woman.

Pederasty was different across the Greek world , one source even sais so telling us that Pederasty is viewed in some places as abhorrent and in others a good thing(EG Theban sacred band I suppose and Sparta were one could argue it was an institution).

Mixed wine seems to be a Greek thing for certain, madness of a Spartan King was blamed(according to Herodotus) upon drinking it unmixed.

Clothing I am no expert in I am afraid.

As for unique Athenian practices , their ceremonies are unique to them(see the Acropolis art for pictures of their festivities). Otherwise I cannot think of anything that is not in someway seen in other places(although I'm sure there are some!).

Basically we cant know how far for sure Athens is representative of Greek culture(legally and governmentally is a much easier question in some respects) , but I believe there were reasonably wide differences, the Greeks may share a language and Gods but otherwise could be as different as chalk and Cheese. Caution is the name of the game with Greek culture and history I'm afraid.

PS trying to work out who exactly is Greek is also a bit of a pain, or what cities constitute as 'Greek' ones. But all these answers ive tried to keep it to mostly the Greek mainland to save a headache.