Get a tackle box and get a crash kit going in it. I had a box with everything in it. ESCs, motors, swappable pods, batteries, a portable charger for 1s batteries, (thank goodness the charging line was bad). It was also my first even but I had practiced fling on a line. The only thing I wasn't ready for was on Saturday the wind was at my back, that was hard to take off into. Also, make sure to teach people who you go with how to be a spotter or a thrower. My dad threw my Spitfire for me once, very sideways, had to put it in the dirt so I didn't hit anyone.
But overall flying events are fun. I had a canopy with a portable table, and a cooler full of food and drinks, and it made it quite fun. I set up on the beginner flight line, and it was great.