Formal:
* Bonjour, je m'appelle... (This is the most formal and polite way to introduce yourself)
Informal:
* Salut, je m'appelle... (This is a more casual greeting, suitable for friends and acquaintances)
* Coucou, je m'appelle... (This is a very informal and playful way to say hello)
You can choose the option that best fits the situation and the person you are speaking to.