Hi. I just thought that I'd try and put all of the info from this forum (http://www.geekzone.co.nz/forums.asp?forumid=48&topicid=109104) and put it into a list of tips.

Process
1. Arrival
After signing up and sending your item to YouShop the following will happen.
If your item is signed for at the warehouse
You should expect to see a notification of a package arriving, and then pay on the YouShop website within 48 hours (this has been known to take longer however)

If your item is 'returned to depot because nobody was there to sign for it'
NZ Post will collect the item within 48 hours.

2. Leaving the Warehouse
The warehouse typically send things out 3 times a week (Monday, Wednesday, Friday). However, if your parcel arrives on a Wednesday (for example), it may not leave until Friday (provided that you've paid for it). Eventually you'll get a notification that it is 'On the way to NZ'. It is expected to take between 5 and 7 working days to arrive in Auckland.

3. Arrival in New Zealand
You will get an email with a tracking number for NZ (often looking like 'CTxxxxxxxxxNZ'). Often this can take a few days to arrive, even though the item may have been in Auckland for a while. (In my case, it arrived on Monday, but I only received the tracking number on Thursday).
Should this item be shown up as 'Held for clearance' you have a couple of options.

a) Wait for a letter
The standard procedure is for NZ Post to send a letter with the customs detail, and the total due. This does not include the $135.82 fee from NZ Post to facilitate the clearance through customs unless you specifically ask for the service. In most cases you can pay Customs directly yourself.
This letter typically takes 1 to 3 working days to arrive, and it has all the details you need to pay customs.

b) (Quick Option) Make some phone calls
The other way of paying customs is to call up as soon as you have the NZ tracking number.
Call 0800 478 287 and press '2'. Then give them the tracking number and ask for the Customs entrance number. This service often goes to voice mail, and I've heard that they're hopeless at checking messages. The best way is to keep trying the number until you speak to a real person.
Once you have received the customs entry number (mine was 8 digits long), call 0800 388 437 and press '2' to pay via Credit Card. 

4. Arrival at your address
Following your parcels release from customs (or not actually going through customs), you should expect to see it within a few days.

Costs to expect
Watch out for customs duty/GST. You can find out if you'll be charged here: http://www.whatsmyduty.org.nz/

Items
Lithium Ion Batteries
"Some electronic items containing lithium-ion batteries can be sent through YouShop. A lithium-ion battery must not exceed 20 Wh/cell, or 100 Wh per battery/pack. Stand alone batteries can not be sent."

Current Deals
YouShopBF1 - 10% Off
Kiwibank10 - 15% Off (one time use)?

Both of these codes do not take this off the compensation cover - only the shipping.

For more details see: http://www.nzpost.co.nz/products-services/online-shopping/youshop/