My first live 30 min minimix

The only real advise for this: Do only what you are 100% confident you can pull off. Do not overdo or overplan the thing. Get tunes you know well and mix then how you can feel confident, do not pull any stunts that might hit the fan.
Prepare 2 sets: One you want to play and a Plan B if it does not pull off the ground. Get the B set so you can easily transition from your A set and have some “sure thing” tracks in both sets.