First car show -- advice??
If you want a trophy, keep the hood closed. I'm not harping on your engine, it just keeps the car lines clean and people seem to respond to that.
I've judged a few local car shows ( still do) and take my girlfriend's VW "hippie" bus to shows. From a participant stand point, we just love meeting people, I bring my 69 Schwinn Lemon Peeler chopper bike along for another reason to chat to folks who had one or show younger kids what cool bikes were made back then.
We let folks take pic's inside or next to the bus and they love doing that. It not only makes their experiences fun, we enjoy it just as much seeing people smile. Now, don't get me wrong, if someone tried to deliberately steal something from inside or scratch it, a completely different side of me would come out.
Don't sweat the small stuff, get it cleaned up to the best of your liking and be prepared like others said to have ALL kinds of conversations!
Lastly, when I'm judging, if the hood or trunk isn't opened, it's an automatic 10 point deduction per panel.
Our bus gets used for camping, cruising, etc. It had a ton of dings, some chips in the paint and even some that is cracked and peeling, but it's ours and we love showing it to people (especially kids) . It's all about what you want from the show. We never ever expect an award, but we've gotten a few. Go to enjoy yourself, meet like-minded car junkies and you'll see if you like it enough to keep going.
Cheers!