Poop before you go on stage. Thats a word of advice from Jerry Cantrell. I try to live by it.
Seriously though I would have a back up of EVERYTHING and know your rig inside and out especially the weak points. Most nationals stage mangers and sound guys aren't particularly fond of the "locals" so if you have any issues they aren't going to be very patient while you tear apart your rig searching for the reason you're not getting a signal.
The biggest advice is enjoy yourself and be confident obviously there's a reason your band got the gig in the first place so to rock out (if that's your band's thing) and love every quick monent of it.....congrats!
thanks! trying to get a guitar tech for the day so he can help me out as well . and especially since i cant speak korean to the sound guy ahah