It's a brilliant ride, I didn't finish it due to some bad errors - which I'm happy to share, I'd read a few ride reports before and barely anyone mentioned how tough the Ardennes section was!
Sleep- stop and sleep on the first night even if it feels to soon, most sensible people booked the F1 in Roubaix, the second day is hard with loads of climbing, if you haven't slept the next sleep stop is a long long way.
The nights are really cold, in the Ardennes it can drop to zero degrees and below, so carrying warm stuff is essential, it will be probably be to cold to bivvy if you are tired.
Food, carry more food than you normally would at all times, particularly the night there are big stretches where there is nothing open, even in the day options can be limited.
Water- fill your bottles at every opportunity, otherwise you will be running round church graveyards in the dark desperate for water. Lots of properties and shops have outdoor taps - buy a tap lockshield key and take it with you, this will make life much easier!
It's really well organised and a friendly event, the arrivee is excellent, once I'd bailed and had a sleep I spent the day there waiting for riders to return and had a great time!