Visas are required of all short-term visitors even those on the list of exempt countries. They need to apply for NZeTA - New Zealand Electronic Travel Authority. However, even if you're from a visa waiver country, there are still the basic requirements that everyone has to meet. New Zealand does not favour people with criminal records (for example, Mike Tyson was refused) & does not encourage those with severe medical issues to come. If you are in good health and of good character, welcome! You may also need to demonstrate that you have enough money for your holiday and return trip.
It is easiest to apply for an individual visa online, although if you are with a partner or in a group, you must put in a paper-based application. A holiday visa allows you to stay in NZ for up to nine months, but you'll need a passport that is valid for at least a further three months. You are not allowed to work in the country on just a holiday visa. Working holiday visas are available to young people (18-30) for up to 12 months which allow you to do some work to support yourself (but you'll need to prove you have, or can afford, a return ticket). If you're thinking of coming for longer, you can apply for a work or resident visa & for that, you'll probably need a job first - check out this guide to living & working in New Zealand.
Transit visas are one other thing to think about. Depending on how you are travelling to New Zealand, you may need visas for your stopover countries, like Australia. New Zealand itself demands transit visas for those travelling through. This area is subject to rapid change, so it is best to check with your travel agent before you travel for the latest requirements. If you are not from a visa waiver country, then please do plan your visit & allow enough time for the NZ authorities to process your application. Times vary from 20 working days for a visitor visa, all the way through to more than a year for an investor visa. You can see the guidelines here, but please remember working days excludes weekends and public holidays. If you need any visa services, then please do contact us, we will be happy to help.
The paperwork sounds daunting, but in many cases it's very straightforward, and as long as you follow the guidelines, very simple. There are several professional immigration advisors who can (for a fee, they don't provide any free services) assist you, but their services would only really be necessary if you plan to stay longer than for a holiday.