Picture Pro night in a room big enough to hold 3 aircraft carriers. That's GABF.
1) Get the list of breweries you want to hit.
2) Get the map of where they'll be.
3) Map your path and hit all of them.
4) Find the BN booth.
Hang out
there and meet all the asshats.
Drink a lot of water. Eat food.
Ask for short pours. You'll get beyond fucked up if you let them pour big. You can always ask for a refill. Take a sharpie and draw a line where you want them to fill to. Dump the bad ones. There are going to be so many beers that you should NEVER feel obliged to force down a bad one. Remember you will NEVER be able to drink them all.
In addition to the Convention center, you have the Falling Rock a few blocks away. That place rocks, though it will be pretty empty during GABF prime hours.
Most of all, have Fun!