New Zealand is an informal country, so you don't have to be formal. It is good to have basic manners, such as greeting people in a friendly way. New Zealanders are usually friendly. They like to say hello and even talk, even to people they don't know. When you take the bus, say thank you to the driver. There are also basic dining etiquette, such as don't make any noise, don't lick the knife and so on.