1) Bring a phone charger or spare battery with you wherever you go. All of those tweets, check-ins, emails and texts are going to drain your phone so fast you will be running around looking for an electrical outlet before lunchtime. The Convention Center usually has cellphone charging lockers you can use on the upper levels, but also consider bringing a spare battery pack (sorry, iPhone users, that doesn't apply to you) or else carry an extra AC adapter in your bag.
2) Be diligent about your health. Not to sound too much like a mom, but take care of yourself, okay? Go for a run on the awesome Town Lake trails and take some vitamins. With all the beer-swiggin' and hand-shakin' that happens during the week, you are gonna pick up as many unwanted germs as unwanted tchotchkes. So instead of reaching for that mimosa, put some Emergen-C in your water and toast to your health.
3) Get to peddling. Austin is really not a very big town, so this year my friend Monica and I (who are staying a mile outside of downtown) are getting bikes. Cheap, quick and no need to fight for cabs. Plus there are added health benefits (see above) Uber, the private car service I love in SF, is also going to be down in Austin with pedicabs, so put them to work for charity.
4) Create your own parties on the fly. About 20% of your time at SXSW is spent waiting in line for something -- to catch a band, to get some food, to use the bathroom... but when the only reason you're queued up is to get in to a party hosted by a tech company, why not just grab some folks and spill in to the bar next door? Let's be honest, guys: will you really get to meet the founder if you don't know them already? Probably not. It seemed ridiculous last year that people were waiting to get in to a bar for a party when the bar next door was completely empty. Try using Hurricane Party's app to make your own on-the-fly party, or else to tell friends where you're relocating to. And if the Foursquare or Gowalla check-in matters that much to you, guess what? You'll be in close enough proximity to fool the app in to thinking you're there.
5) Create a mobile group to keep in touch. Before you get to Austin, decide which few people you really want to keep up with -- perhaps coworkers so you don't miss networking opportunities, or friends so you can use all the +1s you asked for in your RSVPs. Try Kik (great app which just rolled out group messaging) or GroupMe (uses SMS messages) and hit lots of people at once when issuing only one message.
Wanna meet up in Austin? Find me on Twitter at twitter.com/caren