Be sure to pick up the Athens Public Transport Pocket Map at the airport. There is a stand when you arrive between the doors from baggage claim and the Cafeneon-cafe, but it is worth looking around for. If you are getting a taxi transfer from George the Famous Taxi Driver you can ask him to pick one up while he is waiting for you.
Athens Local Blue
These are the ones you see mostly. Some
are stretched out into two buses. You need to get your ticket in advance
at one of the little ticket booths usually near a bus stop or at some of
the peripteros (those kiosks that sell everything) and in the metro stations. When you get on the
bus you stick your ticket in the little machine and it stamps it. Hang
on to your ticket because sometimes inspectors get on board and if you
are not holding a currently stamped ticket they fine you. There are also
Trolly buses which are generally yellow but can be painted in a variety
of colors and covered with ads. But for some reason the GNTO did not have
their routes so I don't either. For ticket info see Athens
The key buses for you are the airport buses and the buses from Akadamia like the E2 which goes to the sea at Voula, the E22 that goes along the coast all the way to Saronida where the beaches are clean, the A3 and B3 to Glyfada, where they aren't (the tram is more fun anyway). You can also catch these buses on Amalias Ave across from the entrance to the National Gardens.
From Pireaus the A1 and E1 go to Voula. (E usually means express). The 040 goes from Pireaus to Syntagma and the 049 goes from Pireaus to Omonia.
Athens Yellow Trolleys
These are not always yellow
but they are always trolleys and probably the only ones you
need to know about are the 2,3,4,5,9,11,13 which go from the
Vas Amalias entrance to the National Gardens to the National
Archaeological Museum. Unless you are unable to, just walk. The 2, 4 and 9 go up to Kypselis. The 1 goes to Larissa Station.
These are the buses that go outside of
Athens to the surrounding area known as Attika. To get here just follow the directions to the Archaeological
Museum and then keep going three more blocks until you see where Alexandras
Ave connects with 28 October-Patission Street.
There is a little square called Platia Aigyptou and you will see them on
Mavromaton street which borders the park. If you want you can
take the metro to Platia Victoria and walk from there. It is
an easy walk from Omonia and not so difficult from Syntagma
and the Plaka unless you are dragging your luggage. It will
cost around 4 euros by taxi. You can get schedules in the Practical
Info Suburban Buses section
but most anywhere these buses go you can also take a taxi, especially
if you are sharing the cost with family and friends. Same goes
for the local blue buses if you are going to the beach. All the above trolleys that go to the National Museum pass within a block of the bus terminal and the 2, 4 and 9 stop right at it. You can catch most of them on Amalias Ave in front of the National Gardens (your back will be to the park or else you are going in the wrong direction).