1) Try a caffeine gel if beginning to feel sleepy and don't just automatically stop for a power-nap.
I stopped for a roadside sleep shortly after Fougeres on the way back, partly because I couldn't find anyone to ride with. As soon as I laid down, a group of about 25 rode past at a good pace. When I woke up, I didn't really feel like carrying on and stopped for another sleep on a camp bed at the next village. At the finish, I had a couple of caffeine gels left that might have saved me at least one of those stops.
2) Set alarm for any roadside power-naps
I always used to do this, but this year I couldn't be bothered, so slept longer at times than was needed.
3) Don't forget to carry some savoury snacks.
I'm vegetarian and took some Quorn sausages to France with the idea of eating them during the PBP. I forgot and left them in the fridge in our wood cabin. It would have been nice to have something savoury rather than just having energy bars. France lacks the delights of traditional British garage food. My favourites being cheese and onion pasties, cheese ploughman's sandwiches and egg and cress sandwiches.
4) Consider using a bar bag as main bag.
There were quite a few riders with nice big traditional looking bar bags. My main bag this time was a 6 litre, 3kg seat post bag. This would have been good if it's rack hadn't broken on the first day, however it also meant that I couldn't use my carbon seat post which would have saved weight and added comfort. Ideally I'd like a light aerodynamic bar bag that gives easy access to my stuff, especially food for eating on the move.
5) Consider the 80 hour start.
I was a bit worried about choosing the 84 hour start this time as it gives away 6 hours potential overall time and makes some of the intermediate controls a bit tight if things go wrong. I had a bad back going into the event, so wished I'd given myself the full 90 hours. Lucky for me though my back sorted itself out during the ride, enabling me to stop taking the painkillers and ride faster than expected. Although the 84 hour start worked very well for me, I'd probably have done a quicker time from the 80 hour start. Still undecided as I'm not keen on the mad, road race style start and I'd probably have finished in the early hours of Wednesday morning, making it trickier to get back to accommodation than my 7pm Wednesday finish.