On my first couple of trips to Europe, back before the Internet, I lugged with me Let's Go France, Let's Go Paris, and the equivalent guidebooks for Great Britain and London. I have vivid memories of some of the most useful information in these guides, which were published by Harvard students and intended for those trying to travel on the cheap.
Generally, the opened with sections on how to get to a country and how to get around (from an airport to the nearest big city, how to use local transit systems). They included useful stuff about phone systems (a big mystery to anyone who'd never dialed an international call), currency, how to tip, and how the washing machines worked.
An awful lot of this stuff seems to have been dropped from current generations of guidebooks. I bought the Lonely Planet guide to Germany, and I think I am going to leave it here. It is a bit out of date (the Let's Go guides were revised annually by student travelers) and is seriously lacking in practical how-tos without having anything to balance out the lacks.
I'm a bit surprised, to tell the truth. I used the Lonely Planet London guide on my five-week trip there in 2004, and that was a great guide, with detailed information not only about the big stuff but about the myriad quirky small museums and other delights of London. Oh, well! Thank goodness for the Internet.