Oktoberfest Reservations?

You can find more information on the various tents here: http://www.oktoberfest.de/en/article/About+the+Oktoberfest/About+the+Oktoberfest/Reservations+at+the+Oktoberfest/760/ The tents are really mostly the same, so go early and wander until you find one that has room. If you go during the evening when it's exceedingly crazy, two tips: closed toed shoes (there's always broken glass and a few inches of beer on the floor), and a plastic grocery bag for a purse/sweater to be tied in. You won't want to set anything down on the nasty tables, trust me. You can tie the bag to the metal brackets on the underside of the table while you stand on the benches, then don't forget to collect it when you leave!

As far as I know, only large groups can get reservations. It can be crowded but I've always had good luck eating an early dinner (maybe 3 pm) outside the tents then picking a tent. You definitely want some hearty food in your stomach before you visit to a tent. It seems like there is a lull in late afternoon - between the people who open the tents then get carted to hospital emergency rooms (I wish I were joking about that) and people who come early evening and stay till closing (which is surprisingly early). Pick a tent and stay there. You have to be seated to order beer. If you try to wander from tent to tent, you will spend your entire evening in line. They are all essentially the same experience - an oompah band, sitting at long community tables, some sing-along, and drinking beer - you may want to choose based on the beer being served at the tent. You will have most fun if you get on speaking terms with your neighbors immediately when you sit down. I think your neighbors can make or break the event, so try to have fun with them - maybe they'll invite you out to their favorite club after the fest shuts down (then you can go till dawn).

You can get individual tickets at some tents - and it's a good idea for convenience and to avoid long lines. The webpage linked in a comment before has links to the individual tent sites, from there you can read about reservations (use a browser like Google Chrome that automatically translates the webpages). If you can't get reservations, go EARLY. Before 2pm on a weekday, as soon as they open basically on a weekend. Once you have a seat, it's yours for as long as you want. Keep in mind that it can take a while to get your food/beverage order and so if you think you might be hungry in a little bit and you see your waitress - order then! The tents like to play up the differences but the basic gist is food, beer, a mixture of traditional music and covers (you will hear "country roads" at least once, probably) and table dancing - at least when the bands are playing, particularly at night. To that end, wear sturdy shoes, be prepared to link arms with strangers, expect it will be hot in the tents, and follow the advice about plastic bags to carry your valuables (better yet, bring as as few valuables as possible, things tend to get lost). Remember to pace yourself and it IS okay to order water inbetween beers! Have fun!

So, I was in the same spot you were in last year. After a lot of research it showed that my group of 5 were not going to be able to get a reservation as all tents have a minimum of 10 persons to reserve a spot. In order to get a seat you will need to arrive by no later that 2:30 or 3:00. That's what we did and we were golden, there was plenty of room! The tents start to fill soon after that and people do not leave until it closes a little after 10. I had a blast in the Armbrustschützenzelt tent!