Make sure your documents are up to date and neatly presented in a folder, all 3 times I have been over my docs have been checked. Presenting them in this way makes a nice impression and gets the task done in a couple of minutes.
How's your French? A lot of the smaller airfields self annouce in French only, so it helps to know the aviation basics, heights, circuit positions, take off, numbers. A Few of these are in the front of Delage (French Pooleys)
Wylie's point about fuel is spot on, unless you have a French Total Card, you will generally have to pay cash all the way. Plus you really need to watch the lunch thing, can easily take 3 hours to get fuelled at the wrong time of day.
Other than that if you are putting into a airport, chooses one with a big river, a big bend and a few hills and it'll generally be quite pretty too, e.g Besancon.
It's generally a doddle, very quite, v good atc, lots of the medium size airports have nice restaurants, so at least you wont starve while you wait for food.
One other thing, stay miles away from nuclear facilities and restricted areas generally, they'll shoot you down and ask questions later.
N joy