Formal:
* Bonjour, je m'appelle Chloé. (This is the most formal way to introduce yourself)
Informal:
* Salut, je suis Chloé. (This is more casual, and is often used with friends or people you know well)
* Coucou, je suis Chloé. (This is even more casual and is often used with close friends)
You can also simply say:
* Chloé. (This is short and sweet, and works well in situations where you are already known)
Remember to pronounce "Chloé" as "Kloh-ay".