How to do SXSW Right

First, download the SXSW app. That way you can keep track of what you want to see and any changes to schedules or venues. https://www.sxsw.com/mobile/
Other sources of information are the SXSW website (of course) and the Austin Chronicle (https://www.austinchronicle.com/daily/sxsw/).
Check the weather! It's usually lovely in Austin in mid-March, but still in that odd space where it could be suddenly cold or crazy hot. You'll want to dress appropriately for all the time you'll spend outside between venues. No matter how hot it is during the day, you're likely to be grateful for a light jacket or sweater at night.
Pack light. One new-ish aspect of SXSW is that they will check your bags - if they're allowed - at almost every venue. Stick to what you can have in your pockets or cell phone case.
Bring cash. I know - no one uses cash any more. But there are lots of street performers downtown at this time, and you'll want to tip at least some of them.
Don't drive. Even if you rented a car, your life will be easier if you take a Ride Austin or Lyft downtown. There are also two rapid buses near Crestview (the 801 and 803), and the light rail heads that way, too.
Escape the crowds. I know you're here to see music and films, but Austin has so many other wonderful things. See my other Houfy stories for some places to eat, or visit Barton Springs, the Cathedral of Junk, or any of our other interesting spots.