Take a look at the floor plan before hand and try to map out the beers you want to try. The more popular breweries and beers will have some long lines to get a taste. Many of the smaller "unknown" breweries will have no line at all. When it's released, there's a GABF app that will have the floor plan and part of the app allows you to make notes and comments on the beers you've had. Trust me, after dozens of samples, you'll forget what beer you really liked and what brewery it was from.
For me personally, I try to taste beers I haven't tried before first. I also try to talk to as many of the brewers and owners that are there. Every brewer and owner I've talked to are great and will answer any question I throw at them.
When I step up to a brewery's booth, I usually will pick out the beer w/ "Imperial" in the name. Which brings me to my next suggestion, drink some water and make a home made pretzel necklace to give you something to munch on. I haven't done the pretzel necklace thing yet, but I just may do that this year.
One thing I really liked is the necklace you can buy there that has a metal ring to hold your sample cup/glass securely in it. I think they are about $8 -$10, but this will help you keep from dropping your sample cup, which is important on the members session because your sample cup is glass. Last year's Friday night session seemed like there was someone dropping their sample cup every 10 seconds.
Have fun and enjoy the event. I'll be there w/ some friends Friday evening, Saturday afternoon and Saturday night.