This is strictly personal opinion, and should not in any way be construed as legal advice.
Please, please, talk to an attorney AND a certified tax adviser. Also see if there are any small business advisers in your area. One of my local universities has a small business development adviser to help local start-ups for a minimal fee.
I personally would strongly advise you to set up an LLC. For my state, the cost is roughly $150.
Why set up an LLC? If a client decides to sue you, they can only take assets that belong to the LLC. In the case of a tarot reading business (IF that's legal in your state, county, etc.) your business assets might include a computer, a reading table, a few decks, maybe a few crystals, etc. On the other hand, if you have a sole proprietorship and get sued, then ALL your assets can be seized -- everything you own -- from your house to your bed to your silverware.
Tax paperwork is a bit more tedious with an LLC, but in my opinion, it's worth it to have your personal assets protected.
Again, this is not legal advice and should not be construed as such.
Nisaba, I understand y'all Aussies are not as litigious as us Yanks. We have to be more careful.