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The best way to teach in France is to land a job with the public education system, whether in a grade school, middle school, high school, or even in a university, like me. The language labs I work with are old and hardly work, it's stressful getting to know the phonetic alphabet and making
occasional errors when I speak French in front of the students. It's a challenge getting them to speak in conversation class and in the high school it was hard to get them to stop goofing off and throwing things across the room. But I really can't complain. Especially considering that since I'm working legally in France, I have the right to their socialized health care. The quality of life is very good.

A colleague of mine at the university works in a private language school, too. He, on the other hand, has no vacations, works twice the hours,
and is paid less for it. It's a great way to supplement his income and stay busy, though.

A Spanish friend who was teaching in the high school last year has come back to France, too, and she's teaching in a large company at 35 hours a week all year without vacation and similar pay.

Then there's always the option of jumping right in and flying to Paris to post ads around town and give private conversation lessons. If you're a really driven, self-motivated person seeking adventure with a bit of money to begin with, this could work - but it's illegal.