I travel by cheapest, which is never obvious.
When you arrive at a city by bus or train, you need to then, not later, go talk with the bus station, sit around, ask questions and suss out the prices for buses. If you are lucky, the train station is in the same location.
The only way I can even come close to know the stations of buses or trains is with the guidebook. "Lonely Planet" if the one I use, but not sure it is the best, the guide is going down the tubes fast. Online sites are in foreign languages, and often do not give prices. The Hostel, or Hotel is your next choice for information, double check, ask both, ask everyone.
But, many times the post times are not correct in Hostel. I just left Kosovo, I arrived at bus station, and had to take a different bus to Montenegro, it worked out, but I was lucky.
THERE IS A MYTH THAT TRAINS IN EUROPE ARE CHEAP
Cheapest is probably low cost carriers for long distance.
Jeroen, the agent in Thailand, from Netherlands, who speaks great English has just helped me to buy 3 plane tickets for around 140 dollars.
1 from Greece to Venice
1 from Venice to Malta
1 from Malta to Bucharest
all 3 cost only 140 USD
Then he told me how to save 20 Euros on train between Pisa and Venice.
This is all very confusing, and outrageously expensive if done wrong. (Note, most people believe they got a good deal, and their lack of knowledge is to be protected.... lol.)
This site helps on Trains.
Eurolines is the only bus, I can sort of recommend, they are really a Charlie Foxtrot.
I go to Wiki first to find a company, the click on the site from inside Wiki. In Europe, everyone pretends to be the site and they are getting commissions etc.
Andy Lee Graham on the bus to Albania today.
The Lonely Planet still has value for maps, history, and season, but is sucking for Hotels now, and I do not care about the restaurants or drinking.
Thanks Andy in Tirana, Albania now.