if you've never been, you need to bring some beer and hang out around the track (16th and Georgetown) by the Coke lot on Saturday night...it is a freaking party with everybody camping. You'll hear a bunch of "Show me your tiiiiiiiities" and many girls will oblige. Get there early on Sunday, parking is pretty bad. Plan on walking a pretty good distance if you're not camping.
Lots of people bring ear plugs to the race, don't just bring beer, bring plenty of water and food. They are forecasting rain for Sunday, so I would bring an umbrella or poncho, or both in case of a lengthy delay. If it's postponed, they'll race Monday.
other than that, just get ready to cream your pants after the green flag drops because it is, IMO, the best moment in sports. It is unbelievable how fucking fast those guys go. I've been every year for the last 10 years. I start counting down to next year immediately after the race
You're going to have a great time, where are your seats? I'm sitting in the Paddock on the straightaway right by Start/Finish.
oh, and eat a god damn turkey leg from a vendor...also one of my favorite traditions.