1. Experience the opposite of urban sprawl:
Germany is about the size of the states of Minnesota and Wisconsin together and they have a population of around 82 million people. To contrast, in the US we have about 300 million on a huuuge plot of land, so it’s much more densely populated. Germany is growing in diversity, so you will likely run into folks of many different backgrounds.
2. Speak "Denglisch."
Most Germans, in particular in big cities like Hamburg, Bremen, Stuttgart, Munich, and Berlin speak some amount of English. So whatever German you speak will help, as you will likely be around some people who speak English. As the Germans say themselves, you can do a lot [gesturing] with your hands and your feet. You shouldn’t have too many problems. Feel free to contact the Office of Tourism in places you would like to visit and have them send you some maps and other information before you go. There are lots of opportunities to have city tours in English, too.
3. Marie Kondo your packing style
When you pack light, e.g. 1 backpack and one medium-sized suitcase, you can do your entire trip on the train with a German Eurail pass or buying tickets directly at Die Bahn . German trains are FANTASTIC, the best trains I’ve seen anywhere, and you can forego a 1st class ticket in Germany. Or treat yourself to 1st class!
For 2nd class, be sure to check out the “reserve a seat” option so you know you have a seat reserved for you. Also, on the trains, they don’t always make important announcements (like track number changes for incoming and outgoing trains) in English, however they are now making most regular announcements in German and follow it in English.