There are a large number of language schools in Paris. The large international companies generally target volume sales, while there are many small and medium-sized language schools that concentrate on providing tailored courses aimed at a niche market.
Many of the bigger schools recruit permanently. This is often a result of having a rapid turnover of staff, which can be a sign of low pay, poor working conditions and/or a poor atmosphere in the school. These schools may offer basic teacher-training and can be a good place for first-time teachers to start their careers. (Watch out, though, some of them deduct the cost of the training from your pay if you leave too quickly).
Smaller schools, often privately-run affairs, are heavily influenced by the personality of the management/owner - a professional and friendly working environment will be present if the management/boss is professional and friendly. Opportunities in these schools are not always easy to find, as staff turnover is lower due to the higher levels of staff contentment and better pay. The experience and quality of the teachers is carefully scrutinised, a series of interviews including a test lesson may be required. If you are serious about teaching long-term in Paris, these companies will offer a more rewarding experience with more creative opportunities.
It is therefore vital to visit a number of language schools before making a decision where to work. If you have the opportunity of asking teachers about their experience in a given school then do so - this is perhaps the best way of finding out about the establishment in question.
Here are some places you might look for job vacancies :