Just got back from Italy and have some tips to share.
It is very convenient to stay at a hotel near Termini (train station). There are many shops,fast food restaurants, pharmacies,...in Termini and you will be able to travel by train whenever you want.
Try not to change money in Termini. You will find better exchange rates in the area around.
Metro/bus ticket is valid for 100 minutes. You can use your ticket to ride the bus (one entry), and the same ticket for metro (one entry).
Try to buy train tickets from the machines not the ticket office. You can find special offers and good deals on the machines, especially on weekends.
Most locals don't know English well so it is useful to learn some basic words in Italian.