Teach children the basics first. You do not want to bore them with advance lessons.
Start with the alphabet and then with the numbers. Once you are certain that they have mastered it, you can then move to the simpler words (animals, food, colours...). Theaching children French can be really fun and satisfying to do. When your kids grow up, it will help them boost their confidence as well as boost their chances of getting a good job. Being able to speak multiple languages is a plus factor, especially French. It can definitely add a certain appeal when a person speaks it fluently.
Flashcards with Pronunciation
Posters with Pronunciation