If they give you a number to wear, they should have pins for you to put it on your jersey.

It's best to bring snacks you're used to eating during rides. You don't want to eat something at the rest stop that you're not used to eating because it might not agree with you.

If there's a mass start, they'll have everyone assemble at the start, you'll stand around while they make some announcements, and then they'll let you go. It will be slow at first while you're in the starting bunch. If you use clipless pedals, you'll probably want to keep one foot unclipped until you really get moving.

If it's show-and-go, you check in, get your bike and everything ready, hit the bathroom, and off you go when you're ready.

Before I leave home, I make sure I haven't forgotten anything by doing a head-to-toe check. Is my helmet packed? Sunglasses? Food and drink? Gloves? etc. down to -- Shoes and socks?

Also you might want to bring clean clothes to change into after the ride.

Good luck and have fun!