Do you drop-ship goods to your customers? Until now, goods under $1,000 in value weren't subject to GST at the border. This is all changing on 1st July 2018.
From 1st July, if you are GST registered, ALL goods entering the country will be subject to GST. So make sure that you work this into your pricing!
Also, if you are tallying up your income so far to keep an eye on when you need to register for GST (remember - once you reach an income/turnover of $75,000, you need to be registered), you should include any income from drop-shipping when calculating your cumulative income so far in this 12 month period.
More information is here.