Germany's currency is the Euro, like the rest of Europe. For every one Euro, there are one hundred Euro-cents. The paper denominations begin at five Euro, with one and two-Euro coins for smaller purchases. It is almost always necessary to travel with cash ("Bargeld" in German) because almost all vendors, except those that are more corporate, do not accept cards. If your plastic still uses a magnetic strip, it might be a safer bet to see if your bank or credit card company couldn't give you one with a "chip" for your travels: you will find that most credit and debit transactions are set up for such cards. This is especially the case by ticket automats on train and streetcar platforms.
ATMs are widely available. Check with your bank beforehand and see if it has a partnership with a particular bank in Germany, so as to avoid high withdrawal fees. And as always, let your bank know before you travel so as not to have your card blocked due to "suspicious activity."
German is structurally a very complicated language that is hard to master in a short time, but most Germans speak exceptional English and occasionally French as well. In its larger cities, it is not unusual for shopkeepers or baristas to just speak English in order to expedite the service. But as with any country in which one is a guest, it is an important sign of respect to learn a few common greetings ("Guten Tag," "Schönen Abend noch"), simple requests ("Wir möchten Bezahlen," "Ein Bier vom Fass, bitte"), the smaller numbers ("Eins, Zwei, Drei"), as well as the ever important thank you ("Danke") and excuse me ("Entschuldigung"). Such can usually be found in the back of guidebooks.
Germany has it all: forests that inspired lexicographers, mountains that inspired philosophers, and long, winding rivers that have inspired poets. It also is host to lakes galore, which come in handy in the very warm summers and are inextricable from the German cultural fabric. The Alps creep a bit into Bavaria, which could be a jumping off point for anyone who wants to explore the range into Switzerland, Austria, or beyond. The only thing missing from the land-locked country is a proper beach, but Hamburg feels sea-side enough, and there are enough other sunbathing and water-recreation options that one won't feel the lack.
Germany has a rather robust lake scene, and no matter what city you visit, locals can point you in the direction of the nearest body of water. Lake culture has also always been a very important part of the traditional German lifestyle, and most lakes come equipped with changing tents, paddle boats and even milk bars. The minute the summer sun comes out, these water holes are packed. For the body-shy, don't believe what they tell you: only a small section of every beach is actually nudist, although topless sunbathers should not alarm. For those who are nudist or nudist-curious, the clothing-optional sections are also the product of a long-standing German tradition, that of FKK, or Freikörperkultur ("free body culture"), a movement started in early twentieth century, based on a pagan return-to-nature notions that experienced a revival of sorts in the DDR.
Germany is incredibly bike-friendly: whether for long-distances or simply cycling around a city. For a small charge, bikes can be taken on all regional trains (but they forbidden on the high-speed rail). In any of the country's cities, biking is a good way to save money on public transportation and the preferred local way of getting from point A to point B. For the sportier tourists, don't miss the Moselle cycle route and the country-wide Radnetz ("cycling network").
Excepting the frigid winter, sometimes its best to skip the bar and purchase beer at a "späti" (convenience store) or kiosk and have in a nearby park or perched on a wall. The drinking laws in Germany allow for outdoor consumption and the carrying of open containers, so there's no need to fret about conspicuous consumption. Purchasing beverages at one of these smaller stores is a quick way to avoid paying premiums at the tavern for what is usually a wider selection of the same quality.
German trains are world-famous for their cleanliness, punctuality, and expansive reach within the country. There are almost no places in Germany where one cannot get by train. Whether you want to city-hop and take an excursion to a nearby lake, there will be a train for you. The types of trains are divided into two main categories, Regional and Inter-City, the former cheaper affairs that you can take your bike onto (but often you have to pay extra), and the latter speedy trains that are more expensive. On the trains themselves one can always choose between first and second class.
Because of the extensive reach of the trains, the tourist should only look into renting a car if they wish to reach more mountainous, out-of-reach places or appreciate the autonomy (also, for the speed-demons: the Autobahn is also notorious for its lack of speed limits). But for the budget traveler, the incomparably cheaper alternative to traveling by train is using BlaBlaCar to find a "Mitfahrgelegenheit," or rideshare, that takes you where you need to go. Luckily for you, the Germans are as passionate about hitchhiking as taking the train, so there are likely rides leaving all day long from whatever city you are in to the next on your itinerary. If you're really into roughing it and/or trying to get away with paying nothing, often all you need is a piece of cardboard with your destination on it-- just ask a local where you would most likely get picked up.
Another cheaper alternative to the train, and less of a social workout than riding multiple hours with strangers in a rideshare, are Germany's long-distance buses, which cover all of the country and many destinations outside of it. MeinFernBus is the most popular carrier, but look around for the cheapest and most convenient option. For those with tight schedules, though, it should be known that the buses often experience delays because of traffic.
Flying from one city to any other in Germany would be overkill, but it's possible. Also possible, and a really good idea, is to take advantage of dirt-cheap flights with budget airlines like Ryanair from Germany into other countries. Sometimes tickets run for as low as 5 Euro, though you can often only take a backpack along with you.