I spent the weekend down in Munich and did the Octoberfest for the first time. So, I will offer this advice.
1. Make reservations (hotel, fest tent, etc)....months ahead of time.. If you want a room in the city....better plan six months ahead. If you want to get a spot at a fest tent without having to wait hours.....better make a reservation at least sixty to ninety days out.
2. You don't have to stay in the city for hotel options. I stayed in Zorneding (about ten miles to the east of Munich), and they have a fine hotel in town.....within 15 minutes walking of the S-Bahn station. Free parking and less hassle, if you ask me.
3. If you hate drunks and chaos.....don't go. Out of the 200,000 people there on Saturday.....I'd take a guess that 10,000 were lightly drunk and 3,000 were extremely drunk.. If that sort of behavior bothers you.....don't go.
4. Food is abundant and you can eat for around twelve to fifteen Euro. You can also eat away from the fest at dozens of fine places in the city.
5. If using the S-Bahn, consider buying a group ticket (all-day deal) for five people.....for around 14-Euro. It covers all zones.
6. Monday through Friday are usually fewer people.....Saturdays are exceptionally crowded.
7. Location? Get to the Hauptbahnhof (main station) and walk out the front door.....heading to the right. It'll take you fifteen minutes to get there. You can use your bahn ticket and ride the U-Bahn there (first stop), but it's crowded like heck after 9AM.
8. Forget about parking in the city unless you have hotel deal. Park way out in the 'burbs' and stick with a Park and Ride deal with the Bahn.
9. If with a group, have an emergency meeting point at a certain time....if you get lost.
10. Nothing is really free or cheap. Per person, for a twelve-hour period.....figure at least a hundred Euro to be spent for beer and food. My advice is to plan for six to eight hours max, and then have dinner in the city.