In terms of tops for travelling, I tend to opt for one or two singlets (depending on weather forecasts), a relaxed-fit tee in black, white or grey, one fitted tee and an oversized cotton men's shirt. This covers all your bases - The singlets are for everyday wear on rotation, the relaxed tee for when it's too hot to wear anything but society demands you do and the fitted tee can be dressed up for going out. The men's shirt could be swapped out for any loose-fitting cotton shirt. It works as a cover-up at the beach or barbecue, but can be belted and worn with heels for dinner. It has to be a natural fabric, though, so it breathes in the heat we're all hoping for.
BOTTOMS
You'll need three pairs of shorts (one denim, two cotton blends, different lengths) or dresses/skirts and one pair of long pants for nights when it's a bit cooler. Depending on your location, a nice printed pair of cotton slim-fit pants would work a treat, as would a nice neutral pair of wide-leg pants. I always take a pair of dark denim jeans in case the weather packs up and I need something a bit warmer that can be dressed up or down. A maxi dress/skirt or two won't go astray either. They roll up to a small size in your bag and can be thrown on at the beach or dressed up for evenings. They're also perfect for Boxing Day, when you've eaten too much to be able to do up your pants.
OTHER BITS AND BOBS
Don't forget you'll need at least one belt, your swimsuit, sunglasses and a hat. I like to take one wide-brimmed hat for glamorous lounging at the beach and a straw fedora (or something similar) for around town. Roll your belt and pack it inside your shoes to save space.
I would also suggest packing at least one pair of statement earrings, whether that's giant hoops or chandeliers, as they're perfect for dressing up a tee and blazer for dinner. Speaking of blazers, I always take one lightweight jacket that can be dressed up or down. A large silk scarf is also a good item to pop in for cooler evenings, or as a cover-up at the beach.
LAST BUT NOT LEAST
Don't forget to take sunscreen and a daily facial moisturiser or BB cream with a high SPF. It is an everyday non-negotiable. The New Zealand sun is harsh and the last thing you want is people tagging you as "the lobster" in your holiday snaps on Facebook.