Reddit reviews The Bogleheads' Guide to the Three-Fund Portfolio: How a Simple Portfolio of Three Total Market Index Funds Outperforms Most Investors with Less Risk

Firstly, have a read of the investment order for new investors.

Then, if you have an emergency fund and no debts (besides HECS/HELP), then

• If you will be using it for something specific in the next 5-7 years (car, holiday, house deposit, etc), put it in something safe such as a term deposit or HISA. The stock market is not a bank account, you need to be able to allow time for your investment to recover from the ups and downs (well, the downs anyway).
  
• If you can leave it in there for at least 5-7 years, you should educate yourself on investing and create a plan.
  
  These are where a lot of the info in the above site came from, minus the Australian-ised part. I'd recommend them too, they're excellent.
  
  JL Collins Stock Series
  Road Map for Investing Success
  Passive investing guide - Monevator
  Bogleheads
  
  If you prefer books to sites (often laid out better), then
  
  The Simple Path to Wealth - JL Collins
  The Bogleheads' Guide to the Three-Fund Portfolio

• Big Mistakes: The Best Investors and Their Worst Investments - to learn that even great & smart people in history have made many, repeated, poor investment choices.
  
• Dark Pools: The Rise of the Machine Traders and the Rigging of the U.S. Stock Market - to learn about how the modern market runs and about all the smart people you're up against.
  
• And finally good news: The Bogleheads' Guide to the Three-Fund Portfolio - to learn that investing doesn't have to be that complicated. Buy diverse, low-cost funds and hold for a long time.