I've gone the last couple years. For the first day, you line up the night before and they distribute wristband. Then on day one you line up and they cut off your wrist band and give you a ticket at the door. At the end of night one, you go outside and line up again and get a wristband for day 2. On day 2, line up, cut the wristband and get a ticket at the door like day 1. For day 3 you just show up at the door and they give you a ticket. There are no lines for day 3 really.
I've been for about 7 of the last 8 and it's been the same situation each time. There is normal a web page on nfl.com that has the info but I'm not sure if they updated it for this year yet. The only tickets I know they sell is through the NFL on Location program but those are expensive and include all kinds of other stuff.
I've actually never made it the night before day 1 because of flights so I normally have to buy a wristband off craigslist for day 1.
I'm not sure if they will be doing tickets with the new city and venue.
Another place to watch is 1iota.com . They give away free tickets if you register and get them when they become available.
Here are some helpful links:
I'd highly recommend going if you get the chance. They have projectors with the NFLN and ESPN video and they give you little radios to listen to either feed so you don't miss anything by being there. Plus you get to boo Goodell in person!