Read up on the public transportation systems available in the area you’re visiting before you get there — then use it. Learning the quirks of the system from the comfort of your own home can save you a great deal of trouble on your trip. Refer to message boards, guidebooks and good old Google to find out lots of information.
Between buses, subways/metro, trams, trains and trolleys, you can get anywhere you need to be using public transportation in Europe. Automated ticket machines have made access a whole lot easier over the last couple of years, but sometimes that’s not a viable option and you’ll have to (gasp) get face-to-face with someone to buy your ticket. We’ve actually saved quite a bit of time and money by chatting with the ticketing agent … sometimes they can guide you toward options you didn’t know existed.
Don’t forget to consider overnight trains between destinations … we’ve taken a few (between Budapest & Krakow, then from Krakow to Prague) and actually enjoyed sharing a compartment with others (though private compartments are assuredly the way to go if you have the money). We made friends we still keep in touch with today through this experience, plus saved a few nights’ hotel expenses and arrived really early to each destination.
Plus, public transportation is efficient, inexpensive and a great way to get to know how the locals live. Watch your pockets, wear a moneybelt and enjoy the show!