Welcome aboard. Probably your best bet will be to meet cruisers in NZ, Auckland
, Whangarei, Opus, and find our how interested they might be in taking on crew.
Some cruising couples are quite open to having inexperienced crew; others look upon it as a potentially making life more difficult, so don't expect it to be easy.
If all you have is a pair of eyes, it's not much to offer as a crew person. If you have sailing experience, it would be wise to add that to your post, or in response to this post.
It might help you to understand that some cruisers are following a long-held dream: they've put hours and dollars into making it happen for them, and taking on freeloaders who may become a real burden due to seasickness or other undisclosed difficulties may be repellent, where others may be far more welcoming.
Good luck, I hope you get a ride, and that it is good. However, just as there are crew from hell, so are there skippers from hell. So, trust your gut, and don't let the lure of the adventure push you to leave with someone when your gut's saying, wait a minute.
IMO, taking on unknown crew and crewing
on unknown skippers boats are both extremely potentially dangerous events
. Comments based on 28 or so yrs. cruising.