I haven't specifically flown in Italy or Greece, but I would assume they would both have similar restrictions/laws on drones as the rest of the EU.
In the past year I've flown my P3S in Austria, Hungary, Czech Rep, Mexico, Sydney, Melbourne, San Sebastian and Bilbao and have had everything from very smooth flying and no issues, to someone very adamant that I couldn't be flying it and threatening to call the police (Prague) and all sorts of lost connections from what i think was concrete/wifi interference (which, if you don't have an annoying P3S then you'd probably not need to worry as much).
I simply complied with what seemed like standard EU drone regs (<400ft, not at night, not over people, >100ft from buildings, etc). I'd search for any country or location specific laws and regulations and print them out and have with you. FWIW, and where having the specific regs on you would be handy, some police officers in Sydney were very nice yet mostly ignorant to the actual laws. Having the printout definitely helped and provided a bit of credibility that I not only knew what i was doing, but planned ahead to comply with local laws. And would probably help immensely if you don't speak the local language well or fluently (aka have the drone regs in local language).
Hope this helps. If you have any other questions let me know.
