FYI： 我們用的買歐洲火車票的網站

For Europe travel, we always buy our train tickets online using trainline.eu (https://www.trainline.eu/search/, note not trainline.com).  It has access to all train systems (except CP in Portugal), is very reliable with no surcharge.  In Italy (or France and other places), for long distance, fast, or private trains, it's always better to buy tickets ahead of time (say two weeks ahead in low season).  The early ticket price could be half or even less than buying them on travelling day, and also save time at the train station.  For trip involving multiple trains, we normally buy tickets separately for each leg, and leave enough exchange time to count for possible delay (which could happen more often in Italy). 

葡萄牙：https://www.cp.pt/passageiros/en/buy-tickets

西班牙：https://www.renfe.com/es/en

各個國家全部可以用電子票，不用打印出來。