How do you get here? Well, by airplane is the most obvious answer. Rome has got an intercontinental airport, Leonardo da Vinci, in Fiumicino and is well served by many European low-cost companies landing in the other, smaller roman airport, Pastine, in Ciampino. Cruise ships stop in Civitavecchia, only 70 kilometers from Rome. All trains going from northern Italy to the South stop here. And of course there are many highways leading you to Rome, if you want to come by car or use the cheaper bus option.
Once you are here, underground and city-trains should be your first choices to visit Rome. Buses are actually very slow and often unreliable. Public transport is very cheap but after 11:30 pm, it is no longer a viable option. Watch out for your wallets, always.
Taxis are not cheap and sometimes cab-drivers cheat tourists. Otherwise, you can rent a scooter but driving in Rome is not easy. Forget about going around by car! You can’t use it, especially if you want to visit downtown Rome: parking is impossible, there are many traffic restrictions and you would lose yourself easily. If you are in good shape, you can rent a bike, but remember: Rome was built on seven hills…. Furthermore, Romans are not very disciplined drivers!
If you need some preliminary orientation sightseeing buses may be very helpful: they go nearly everywhere in downtown and some even go further.