You have the option to drive around yourself or book with a company who will give you a tour. The former requires you to navigate and the latter requires you to adhere to the tour schedule; consider your options before you arrive. There is a fair amount of elevation gain throughout the day, so individuals who are sensitive to high altitudes ought to be prepared for any sickness. You may be required to have a travel visa depending on the passport you hold. For others a visa may not be required for trips shorter than 90 days, but a passport is required to enter the Schengen area (which comprises 26 countries, including Italy).