Get plenty of rest before you arrive. we go non stop.
Go with the group. A laid back atmosphere is critical in Bavaria
Eat a lot of food. It will provide a good base for the beer
Try new things. Even if you have never had Haxen, and think it looks too much like a pig knuckle, try it anyway*.
Sleep on the train. Just make sure there is someone awake to make sure you get off at the stop.
Check out the German Rail Passes. They have 3 or 5 day passes that allow you to go on the DB and S-Bahn lines. In the US you can get these at AAA. The only issue is that the twin passes require you to travel together (i.e. you get one pass)
Make sure you try the Gyros in the little shop near the Hotel Alfa. ask for them 'spicy'.
Don't ask for wine at the Beer Tent
Don't ride the upside down rides after eating a hendel, a bretzel, 2 sausages, a radish, and 4 Maß of Bier.
For $50 they will let you lead the band.
They don't serve ice like they do in the states. Even at Burger King. In fact, the Burger King doesn't make ice until after 11am. even then you get one cube for a big gulp.
Try not to attend over the daylight savings time change. They get really confused, as do you. You may even show up early for your train.
Wear comfortable waterproof clothes. between the rain and the beer, you need to keep dry. Many times we will leave the hotel early in the morning and return early the next day.
Never, under any circumstances, look inside a sausage.
Never sit at a table with a sign on it that says something scary in German
Make sure you sit near the Aussies and Kiwis in the beer tents. Have your camera ready at all times.
Have fun, enjoy seeing old friends, and remember, What goes on in Munich, stays in Munich.
*Note: This rule does not apply to Tuna fish pizza.