A couple of points...

I always printed my DB tickets on US letter paper until one day a conductor gave me a long stare before stamping it. So I ordered a ream of A4 paper from Stapes -- picked up at my local store so no shipping. A ream is a lifetime supply but I consider it insurance against nitpicky Euro conductors. Before anybody gets upset -- 95% are wonderful but I have been burned by the 1-5% that love their authority.

And on the Bahn Card -- you can usually buy it with your ticket online -- normally it is for a year but DB has special versions from time to time for shorter periods (3-4 months IIRC). It can easily save you the price the Bahn Card and more but there is a catch: If you don't cancel it in writing within a fairly specific window before it expires, DB will renew it and send you a bill. And if you ignore the bill the will send it to a collection agency and bug the hell out of you. A few years ago a bunch of us bought a long haul ticket at the station and the agent told us a Bahn Card would save us a bunch of money so we sprang for it. So 14 months later we all get nasty letters from DB and six months after that collection letters from a Dutch collection agency. That is they way they do lots of things in Germany -- you must opt out or you are renewed. Not saying that is bad, but it is different than in the US so be aware.