You can travel to Italy if you have a passport that's valid for three months after the date you plan to depart the country. You don't need a visa for trips to Italy for a period of 90 days or less.
The items you'll need to take depends on your selected Italy tour, any activities, and the time of year you'll be travelling. For example, hiking and trekking tours will require sturdy footwear and appropriate clothing. Choose lightweight clothing for the warmer summer months and take sun cream and a hat. For colder months you might consider layers and waterproofs.
Other items come down to personal preference, but you might wish to include a camera, phrase book, and swimwear.