That attire is definitely appropriate. Nothing in particular to be aware of. If you can rent a car, do so. It was so cheap and we were able to do all of the things that NCL offered as individual excursions. We found the beach just riding around town. We also went on a boat excursion around the coastline for like 60 euros for 4 people. We did the achilleion palace tour and just enjoyed the freedom renting a car provided for us. We got back in plenty of time and even had time to do some shopping. It was my first cruise and I planned all of the excursions instead of going with NCL. The savings were tremendous - instead of paying 1000+ for 4 people, I paid under 400. Don't be afraid to be adventurous. Just be sure to keep track of the time.