Use honorifics and family names when addressing people unless invited to use first names, and add polite forms like "Sir" or "Madam" in formal settings. In Sinhala and Tamil contexts, people often use respectful terms such as "
Aiya" for an older brother or senior man and "
Akka" for an older sister or senior woman, and in business or official interactions it is safer to be overly formal than too casual.