Formal:
* Até breve! (Ah-tay breh-veh) - This is the most common and neutral way to say goodbye, meaning "see you soon."
* Até mais! (Ah-tay my-ze) - Similar to "até breve," but slightly more formal.
* Até a próxima! (Ah-tay ah pro-shee-ma) - Means "until next time."
* Um abraço! (Oom ah-brah-soo) - "A hug!" This is a friendly way to say goodbye, but it's more common among friends and family.
Informal:
* Até já! (Ah-tay jah) - This is a very informal and friendly way to say goodbye, meaning "see you later."
* Até mais tarde! (Ah-tay my-ze tahr-deh) - Similar to "até já," but a bit more formal.
* Te vejo! (Teh ve-zhoo) - This literally means "I'll see you!" and is a very common and casual way to say goodbye.
* Tchau! (Chow) - This is a very informal and casual way to say goodbye, similar to "bye" in English.
More affectionate:
* Até logo! (Ah-tay lo-go) - Means "see you soon" and is more affectionate than "até breve."
* Até mais, meu bem! (Ah-tay my-ze, meu bem) - Means "see you later, my love" and is only appropriate for someone you are very close to.
* Com saudades! (Coom sow-dah-dees) - Means "miss you!" and is a very affectionate way to say goodbye.
The best way to choose the right phrase depends on your relationship with the person you are saying goodbye to. If you're unsure, it's always better to err on the side of formality.