Occasionally, VISA cards not issued in Italy, may present a problem at the train station. Cash is king. Having said all that, train travel is relatively inexpensive when traveling alone or as a couple, even so you must consider the bag-dragging schlepp factor.
The 2nd class fare from Florence to Bologna, for example is $10 on a slower train. Add an $8 'Supplemento' for a faster Pendolino train and another $10 plus for the cab to your destination. If cabs are not your style, try taking the bus for about a dollar. (see the bit on buses).
Finding the station is easy, look for the FS signs, not to be mistaken for Fast Service but for Ferrovie Statali (state rail). On trains, by each six seater cabin there is often a slot with sheets designating reserved seats. Failing to heed this you may end up having to rise at the last minute, especially when all other seats on board are taken.
Train lovers take heed, ciuccio the Italian word for donkey sounds very, very close to Choo choo!