Recently, my wife, Liz, and I were fortunate to host visitors from Germany, friends we have known for several years. One of them travels the German rail system frequently and told me he often does so without a seat reservation (it is possible to have a ticket or rail pass that allows the ticket/pass holder to ride the train but does not provide a reservation for a specific seat). I explained to him that many Americans, even though they have a rail pass or a ticket, are leery of boarding a train not knowing where they will sit. My friend offer these tips:

• Advance reservations are usually not necessary, even on ICE trains. The exception to this is on Fridays and Sundays, when trains can fill up. I should also point out that some ICE routes require reservations. You can find out which ones at the German Rail website.
• All seats in dining cars are open to anyone and you can nurse a beverage for an entire trip.
• A maximum 70 percent of seats on German trains are eligible for pre-booking. That means the other 30 percent are on a first-come, first-served basis. If you are traveling from the train's point of origin, just go early and grab one of the unassigned seats. If a Berlin-to-Frankfurt train originates at Berlin's Östbahnhof before stopping at the new Hauptbahnhof, where the majority of passengers will board, my friend simply gets on at the originating station, Berlin's Östbahnhof.
• Reserved seats on German trains are noted by a small card or ticket on the luggage rack above the seat. A seat marked in this fashion may be empty. Check the card to see if you can occupy it. If, for example, you're on a Berlin-Frankfurt train and the reservation card says "Leipzig-Frankfurt," then you are free to sit in that seat between Berlin and Leipzig. If the card says "Berlin-Frankfurt" and the seat is still not occupied 15 minutes after the train has left the Berlin station, then the reservation is no longer valid and anyone can sit there.
• If, in addition to whatever rail pass you've purchased, you want a seat reservation on a specific train, at least wait until you get to Europe to book it. Reserving seats in the U.S. from is expensive; at least $11 per seat, plus the cost of shipping—about another $18. Throughout most of Europe, on most trains, the price is three euros. If you have a rail pass that covers Germany, and must have a reservation prior to your U.S. departure, the best place to do that is online. At the Website, begin the process as if you're purchasing a ticket for the train on which you want a seat. At a certain point in the process you'll note a "seat reservation only" box. Check the box, finish the process, and print your reservation.

Of course, for most German trains—short-haul, regional trains—reservations are not even possible. In any case, I can't remember the last time I was on any train in Germany where every seat was taken. Never, during a recent four-week wintertime trip, did we ride a car more than half full. One afternoon in an ICE restaurant car between Dresden and Berlin, we were attentively served a hot meal and bier vom fass while watching the countryside roll by and the day turn to night. Except for the two servers and one other customer, we were alone.