We spent 3 weeks in France, taking a train to Chartres and renting a car there. We drove south to the Dordogne, west to Charente Maritime, and then north to Normandy. We left the car in Caen and returned by train to Paris.
I did most of the driving and my husband the map reading. One tip is to be familiar with the names of towns on the way so that you recognize which directional signs to follow. (At least with round-abouts, you can circle if need by while you figure this out). We knew the names of larger towns along our way, but sometimes the road signs were for more immediate towns and we needed to check them out on the map to know which way to go. (Love those round-abouts!)
If you are on a freeway, remember the left lane is for passing--and then get back over right away. Cars driving much faster are used to this and they will be on your tail.
When we were in Brittany or Normandy, we noticed one of our turn signals was burned out. Even though we were driving a Peugeot, we stopped at a Renault garage and they replaced it for us. Our two sons were in a French Immersion elementary school then, and the man at the garage was teaching them lots of new vocabulary on car parts.
Normandy residents were very friendly to us as Americans. Don't miss Utah Beach,Pointe du Hoc, Le Mémorial de Caen, un musée pour la paix - "The Caen Memorial, a Museum for Peace," and cemeteries, too.