You asked this under "Australia"... right...
If you're an Australian, it's fairly easy, but it's not too hard otherwise I don't think, as long as you don't have a criminal record and go through the right procedures - check and double check about ALL the paperwork you have to do, or else they'll just send you back home.
Check out the Immigration website - http://www.immigration.govt.nz/
You should do it - I love my country, I'm sure you will too