Casual / Slang (friends, peers): "Fa'afetai?" — Literally "Thanks?" but used colloquially like "What's up?" or "How's it going?"
Respectful / Standard (elders, formal, strangers): "Tālofa lava, 'oe ā 'ea?" or "Tālofa, pe 'ea 'oe?" — "Greetings, how are you?"
Cultural note: Samoan society values hierarchy and respect (fa'aaloalo). Default to the formal version unless invited to be casual.