I agree with the points made just above by Paul-of-the-Frozen-North about the required driving skills
a few that I consider critical:
Understand the National speed limits (and Departmental idiosyncrasies) so intimately they are in your blood so you don't need the (sometimes missing or vandalised) signs, and what a settlement name means on a sign and one with a red diagonal line.
Completely understand the meaning of a yellow diamond, and a line diagonally across a yellow diamond, and react appropriately when you see a sign reading, "Vous n'avez pas la priorité". Understand that if you wind up on the Boulevard Périphérique (usually known just as Périphérique) in Paris, the rules are upside down and the experience can be interesting.
Be ready when you reach a Péage (toll booth) to be in the correct lane for your method of payment. Understand that, like on a turnpike, sometimes you pay at a Péage and sometimes you take a ticket (ticket or billet). There are a few Autoroutes which are "Free Flow" where your number plate is captured by a camera and you pay on line. There will be signs on the side of the road - have your co-pilot make notes.
On the Autoroutes, at the Aires, service areas, both big and small, beware the "seat thieves" and at the smaller ones which often use the floor hole method, no seats at all. Practice holding a squat. Take tissues or a travel roll -sometimes there isn't any.
Get your IDP (International Driving Permit), one for each driver to be used with your home licence, before leaving home. If you get across the water without one you can be stuck.
The colour of the filling station hose and nozzle may very well be opposite or just different to what you expect. As they say, measure twice and cut once. Gasoline/Petrol is "Essence", Diesel is Gazoil or Diesel. Don't assume that gazoil is gasoline. It isn't.
Fuel is priced by the litre.
Rappel means the previously indicated lane or speed restriction still applies.
Understand the differences and driving style differences between A, N and D roads.
Keep right except to pass. No passing on the right. The French use their turn indicators differently. You'll be able to tell which country a car is from by its driving technique and skill without looking at the number plate.
Seriously - best to bone up.
Bonne Chance et Bon Voyage
