In France it’s best to stick to formal forms of language (vous, etc), unless you know people well. Using first names, nicknames or terms of endearment for people you’ve just met would sound strange and rude. Younger people don’t tend to worry about such things as much though.
Punctuality tends to be quite approximate in France – arriving somewhere 10-15 minutes late for a party, for example, is normal and polite. Arriving on time could be seen as rude as it might not give the hosts enough time to prepare everything.
When eating in France it’s normal to put your hands and fore-arms on the table, though not your elbows, which is rude. Forks are normally laid with the prongs pointing towards the table, a custom that dates back to the French Revolution, and bread is often placed directly on the table rather than on a plate. If you’re invited to dinner, it’s normal to bring something –chocolates or flowers are acceptable gifts, whereas bringing wine is not a good idea as it would indicate that the host’s wine is worthless.
Politics, politicians and philosophy are perfectly acceptable and normal subjects for conversation in France, and the French like to engage in long and sometimes heated discussions about them. They also contradict each other just for fun sometimes, and also to encourage debate. One subject best avoided in France is money, discussion of which the French consider extremely vulgar.
In French offices the workers usually address the management, especially those much higher up the hierarchy, with their titles, e.g. Monsieur le Président, and it’s not usually for colleagues to go out for a drink after work, unless they know each other well.