Formal:
* Olá, meu nome é... (pronounced: oh-la, may-oo no-may eh...) - This is the most formal way to introduce yourself.
Informal:
* Oi, meu nome é... (pronounced: oy, may-oo no-may eh...) - This is a more casual way to say hello and introduce yourself.
* E aí, meu nome é... (pronounced: eh-ee, may-oo no-may eh...) - This is a very informal greeting used among friends or people you know well. It's similar to saying "Hey, my name is...".
Other Options:
* Prazer em conhecê-lo(a). Meu nome é... (pronounced: pra-zer em koh-nyeh-seh-loh(ah), may-oo no-may eh...) - This literally means "Pleasure to meet you. My name is...". It's a polite way to introduce yourself, especially in a formal setting.
Remember to choose the appropriate greeting depending on the situation and the person you are talking to.