>>1001909The #1 tip is to try to be near peak condition for the ride. Do lots of long rides, be prepared for wet, cool, or possibly hot weather. Don't party all night Saturday and have to change to the short route on Sunday morning.
#2 Get your bike ready. In no particular order I saw riders having problems with loose headsets, thrown chains, loose seat clamps, and ineffective brakes. Don't wait until the morning of the ride to find out your downtube shifter clamp is loose and your bike starts shifting by itself. Put on new brake pads, e.g. Coolstop, they're much better than thirty year old Campy brake pads.
#3 Do lots of riding on your Eroica bike. Learn (or re-learn) the muscle memory to get in and out of toe clips without thinking. Teach your hand to move to the downtube shifters. You'll probably have to brake from the drops because the mechanical advantage of old brake levers and brake calipers is different.
(if you also have a modern road bike you'll come to appreciate it even more)
#4 Rules and Enforcement. I think they kinda relied on the honor system, but that could change. So long as you had a steel diamond frame, steel fork, non-aero wheels, downtube shifters, old pedals, and non-aero brake levers, your bike was okay. I saw wool and modern jerseys, lots of lycra shorts, and a variety of bike and non-bike shoes.