Be prepared to lose a day or two, if you do not have the necessary paperwork and someone who knows Greek to speak for you.
Pick carefully your bank by convenience and proximity to your home.
Always order a debit card along with Internet banking, if you know how to use a mobile phone. It will be handy in time.
Piraeus bank gives you the card and internet access codes on the same day.
You can try to change your PIN number at the ATM, but always check that the new PIN works , before you throw away the old one.
You can get the general idea by vising the following link eurobank.gr/en/search?term=open%20an%20account