Formal:
* Bonjour, je m'appelle Livi. (This is the most formal way to introduce yourself.)
Informal:
* Salut, je m'appelle Livi. (This is a casual greeting.)
* Coucou, je suis Livi. (This is a very friendly greeting.)
You can also just say:
* Je suis Livi. (This is a simple way to introduce yourself.)
Important note: In French, it's common to say "Bonjour" at the beginning of a conversation, even if you know the person well.