Navigating in France is actually both easy and hard. It is easy to navigate across the country from one town or city to another. It is extremely hard once you get to the destination city to find something that is not a major attraction (like a hotel).
Basically, to get from town to town, you just need to know some of the larger towns in between where you are and where you want to go. There are signs everywhere that tell you what road to take to get to the next town. Follow those signs until you get to the first destination town, then look for the next town along the route. By hopping from town to town, you can very easily go from one end of the country to the other by simply remembering a few towns or cities along the way.
It is also very easy to find the major sites in a town once you get there because there are also signs pointing the way. Every city/town/village has a sign on the road pointing to the "Centre Ville" which is basically the downtown area. Also, if you are looking for major attraction like a cathedral, chateau, stadium, etc., there will be signs for those.
Where it is difficult is if you are looking for a hotel or god forbid a house. In this case, you are on your own, and the streets are so nutty it is REALLY difficult to get where you're going. The streets change names constantly, they change direction regularly, and go through round abouts all the time. The combination makes finding a particular address quite challenging.
The good news is that we've been successful to date, and every day we get a bit better at navigating. Who knows, by the time we return the rental car we might be experts!