1) Travel First class if possible ;P
2) Make yourself very very tired prior to your journey and try and really sleep as much as possible in flight.
3) Let the cabin crew know you do not want meal service so that you are not awoken from your inflight  slumber.
4) Take a picnic for in case you get hungry.
5) As soon as you get to the other country, have a walk and fresh air - get on the local timetable immediately. Avoid going to bed early, waking up late, etc. It will be hard for a couple of days but you will recover quicker if you shift your body clock onto Italia time asap.
You'll have a blast, have so much fun and enjoy the pizza!