Did you know that unless your business is going to turn over more than $75 000 in the first year, it is not necessary to register for GST?
Depending on what your projected turnover is, you will want to consider this option, as if you believe you will turn over more, then better to register at the beginning and build GST into your business process.

Goods and services tax is a broad-based tax of 10% on most goods, services and other items sold or consumed in Australia. GST applies to most Australian businesses and it's highly likely that your business will be affected by the tax. If your business is registered for GST, you'll have to collect some extra money (one-eleventh of the sale price) from your customers and pay it to the Australian Taxation Office (ATO) when it is due.

For more detailed information see the Australian Taxation Office