US Citizen here. What is common for tipping in restaurants in France (we will be in Loire Valley, Menton, and Paris). When we visited Spain a few years ago, we were told by a Spanish friend that tipping was out of the question, however through our own travels after leaving them (and our compulsory tipping habits) - we found that tips were actually appreciated and generally left around 10% as a kindness.
Is this generally a thoughtful thing to do in France - I do not want to make a faux pas by tipping, but would also like to leave something for good service if accepted?