Unlike the old days in the movies, you won't see porters at most European train stations these days; you'll put the "lug" back in luggage yourself. Between that fact, and the very limited storage for luggage on the trains, you'll want to pack as light as possible. This Lovetripper video, shot on a train between Vienna and Prague, takes a look at luggage on the train:
If you're traveling from North America to Europe this summer for any length of time, you're probably considering a rail pass. They're not cheap but they are a great value if you'll be traveling by train multiple days. (On some railpasses, your travel days must be taken over the period of so many days; other flexipasses allow you to use your designated days of train travel over a longer period.) The train system is a delight; it's such a joy to get away from the airports...plus no early check-in time. You'll arrive right in the heart of the city at most destinations, another budget saver. Here's a video we shot between Vienna and Prague about traveling by rail pass:
Several years ago, we had the pleasure of taking the Rocky Mountaineer scenic train from the Jasper/Banff area all the way to Vancouver, one of the most scenic train trips in the world. This excellent one-minute video takes you on the romantic train with its glass dome observation car and first class service. All aboard!