In the first week , I avoided the transportation system altogether because I simply didn't know how to use it.  Then finally I used the tram with someone who knew the system, and I was able to pick up how to get around the different systems.  So now lately I have felt very liberated, because I have the power to escape our immediate surroundings and see a larger part of the city and the country.  I think I was mostly changed in my ability to cope with the unknown.  Through this experience, I would like to think that my next encounter with an unknown situation will go more smoothly and be less stressful.  
In the long run, I think the skill that will be most improved for me will be versatility.  There was no way to prepare for many things I experienced in Greece, and I had to learn to roll with the punches.  In the future, I think this will serve me well in school and work.