| | Re: Am I running a hobby?
The Government likes to complicate matters - it keeps public servants occupied. There's a couple of issues that spring to mind.
Are your studies anything to do with the graphic design / website work? Are you paying HECS fees?
I'd speak to an accountant or Registered Tax Agent - there's a tax free threshold that people can earn before they start paying tax - there may be benefits of having a business to offset your study expenses etc
According to the ato.gov.au website, if you are supplying goods or services, you will need to be able to quote an ABN so that others businesses do not withhold tax at the top marginal rate when they pay you.
Etc, etc etc - There's no "one answer fits all" - If you are developing this sideline to support you through uni then maybe you should make the decision and go for it.
In your industry, word-of-mouth is a major source of work. You may find your clients refering more work to you, so you may as well be ready and prepared
Good luck with your new venture