Another good idea, when attending any event, is to do a walk-through when you arrive so you know where to go and how long it will take you to get there. Try to arrive at least 15 minutes early since most sessions quickly fill up. Don't neglect to have a back-up plan in case the panel you were hoping to attend is full.
If you do get turned around, there will be Connection Centers set up throughout the Convention Center where you can get directions, or moral support if you're feeling overwhelmed.
Finally, remember all the things your mother told you as a kid; they'll come in handy here too! Wear comfortable shoes, don't be shy (this is a networking event after all), pace yourself (there's a lot to do but you have to find time to eat and relax too), and, most importantly, stay hydrated!
You can see all of SXSW's tips at sxsw.com.