Unless you are coming from outside continental Europe, I suggest you take the train. The parties on these trains taking you to Octoberfest and almost as fun as the event itself.
Once you arrive, you can walk to the beer garden.
The main train station is Karlsplatz and in a convenient spot to transfer to a train from a tram or subway.
Trains from all over Germany and the rest of Europe arrive at the Hauptbahnhof (hbf) or main station. It is on the U & S Bahn too so moving into the city is easy.
Munich was wonderful but it was time to grab the packs and head for Austria. Trains are fast, clean, and on time, a great way to travel.
This is the beautiful Schloss Schleissheim (Schleissheim palace).
You can reach it with the S-Bahn S1 to 'Oberschleissheim' (20 minutes from the train station) and it is well worth the trip.
Munich Hauptbahnhof (Central Train Station) There is also a tourist information.
Public Transport, Bicycle, Rikscha, Taxi, Walking...