Del,
What bike, wheels tyres and gearing did you use? I know people do it on all sorts but there must be an ideal option?
I've got a Ridley, so I chose that bike. Had to ride a Belgian designed bike for Flanders!
I've ridden it each time on 25mm clincher tyres, but as
@CXRAndy said, if your bike will take 28mm tyres that might be worth doing.
I've run tyre pressure around 90 psi on a 25mm tyre. You can go a bit lower. There are articles that recommend tyre pressure setting such as:
https://blog.tacx.com/how-to-prepare-your-bike-for-a-ride-on-the-cobbles/
I've lost a stone in weight since I last rode Flanders. I'm now 11st 12lbs or 75kg, and according to that article I could go a bit lower now, maybe to 85 psi. The main thing you're balancing is reducing the jarring from riding over cobbles, versus the increased risk of a puncture. The cobbled sections are tough but there's far more riding on ordinary tarmac roads.
Some people put extra bar tape on their bars. I don't bother, but try not to grip your bars too tightly when you ride over cobbles. You'll tend to grip harder at first, but try to stay as loose as you can. You have to let the bike bounce around a bit and go where it wants to some degree. It will normally correct itself and stay in a straight line. You'll feel a lot less tired at the end of the ride if you can master that.
When you're riding on the cobbles, there are normally 2 places people recommend. Either ride in the gutter and try to avoid the cobbles or ride on the crown of the road in the middle where the cobbles are normally better, more even and with less gaps. I've tried both, but I've settled for the crown. Riding in the gutter is ok, but your bike handling needs to be good and you need to look well ahead. If you look close to your front wheel, trying to avoid drains, uneven driveways, etc, then your bike handling just gets worse and you're in more danger of coming off. I decided I was better off on the crown. If you're going to ride a cobbled classic, then there's not much point in trying to avoid cobbles!
Make sure you've got good bottle cages! I use metal cages on my Ridley that grip the bottle. I also use shorter bottles. Both of these things reduce the risk of your bottle flying out of the cage when you hit the cobbles. One of the more amusing thing when you hit the first section of cobbles, is the number of bottles lying on the road from bikes where the rider didn't follow this advice.
And finally, treat your nuts to a nice coating of chamois cream or Sudocrem. They'll thank you hugely after you've battered them to pieces over 90 odd miles (or longer) of Belgian roads and cobbles!
Hope that all helps!!