Best advice I can give any traveler: Utilize Hostels.
Do It. They are chock-full of information, and are so excited to help you.
I stayed in a hostel my first two nights in Brisbane and then couch-surfed the rest of my time there. Even though I only stayed in the hostel for a short time, I kept going back because of all the information, computers, bar, and people that congregated.
If I hadn't done this, I wouldn't have had one of the best adventures of my life!
At just about every hostel in Australia, they have organized tour groups that come through and offer travelers opportunities to see the rest of the beautiful country.
The first thing I was advized about Australia was to get a car. I can't afford a car in the US. There was no way I was gonna stick myself with a dumpy car or van in a foreign country all alone. So, I would naturally miss out on the scenery and the out of the way places that Australia is all about.
These tours that come through these hostels offer to see all that I was missing out on (whether I was a customer with the hostel or not!). I ended up touring the 12 Apostles and the Great Ocean Road and my favorite trip was snorkeling old shipwrecks and sand surfing out on an island outside Brisbane!
A guide picked us up outside the hostel at 7:00 in the morning and she drove this big monster truck to the ocean, onto a ferry, and then through the jungle and desert on this island. They gave us wetsuits, snorkeling lessons, lunch, and swam with us through old shipwrecks. It was ultimately my best day in Australia! I was misfortuned to be in Australia during cyclones over the Great Barrier Reef... but this made up for it and then some.
Check out hostels! There are surplus amounts of opportunities throughout Australia! Take advantage.