If you are driving in the outback, be prepared for anything. There is little traffic, so it is unlikely that anyone will be able to stop and help you should you break down.
There are few towns/gas stations etc, so motorists need to make sure that they carry adequate and surplus amounts of food, water and fuel. The interior of Australia is a true desert, so if your vehicle has no air-conditioning, you could suffer day time temperatures of 45° Celsius (110° Fahrenheit). Night time temperatures can drop to freezing.
Depending upon the estimated time of travel and the remoteness of the roads, it is wise to take at least 10 litres of drinking water per person per day of travel, and an additional 3-5 days of extra drinking water per person, in case of breakdown. Shade material and very thick warm blankets are also important survival tools. A box of matches or cigarette lighter should always be carried when intending to travel into isolated areas. A fire can provide warmth and can be very helpful in attracting attention if lost or stranded.
Do not expect your mobile (cell) phone to work if you are in the outback. While efforts have been made to 'cover' the populated areas, large areas of the country do not have service. If you really go to the back of beyond it is a good idea to buy or rent a two-way HF radio (the Royal Flying Doctor Service web page lists outlets they can be hired from) or a satellite phone.
Many outback unsealed roads require a true four-wheel-drive vehicle for safe passage.
One that is especially prepared for the trip with suitable equipment depending on the length, isolation, and roughness of the track. Advanced planning is required for such trips, you cannot just hire a passenger sedan and go! An SUV or soft road vehicle is not always suitable for roads marked as requiring a four wheel drive.
Temperatures can be extremely hot during the day, and can drop drastically once night falls. Always go to the local police station when you are going off the sealed (paved) highway, and tell them where you are going and how long you expect to take. This will help them to look for you if you are stranded.
Never ever leave your car when it breaks down in the middle of nowhere.
In case of a long wait it gives you shelter and it is a lot easier to spot than a person walking in the bush. Also, a person uses about four times as much water when walking, and Australia is a dry country.
Beware of potholes and corrugations on gravel roads.
Potholes are not always visible on sandy roads. The road surface might seem quite even, but hidden potholes hit with sufficient speed can overturn a car. Corrugations are wavelike formations that form on a road surface when enough cars have been driven over it. At low speeds the car will be shaken to a degree that's almost unbearable. At higher speeds there is a risk of losing control over the steering wheel. In most cases a speed of 50-60 km/h is a happy medium; not too slow and not too fast. Do not try to steer around lizards, etc, the car is likely to become unsteerable with a high chance of crashing.
Dust can also be a problem on unpaved roads, and heavy vehicles travelling at high speed often leave a trail of dust behind them, severely impairing visibility in vehicles behind them. As a precaution, do not tailgate. The significantly reduced visibility in dust storms caused by vehicles in front can have deadly consequences.
Some two-way paved roads have only one lane paved, right down the middle. When approaching another car both of you are expected to move left off the bitumen onto the dirt at the side of the road, pass, and then move back onto the black. Be wary immediately after passing, as the other car will have stirred up a huge dust cloud which will lower visibility for several seconds.
Bulldust is a fine talcum powder-like dust that is very common on outback Australian tracks. Patches of bulldust look like smooth hard patches but in fact it usually is a fine covering of dust over a deep hole. Driving through bulldust at speed is very dangerous and must be avoided. It can cause damage if sucked into engines too, so in very dusty areas you should have a filter on your air intake and check it regularly.
Pay particular attention to the weather forecasts in outback areas and be prepared to stay put for a while if the weather sets in. Unsealed outback roads, especially, can be closed with little notice in the wet, isolating communities, at any time of year. If in doubt, check with the local authorities before starting out.
Also watch out and be prepared for Australia's Road Trains.
After all these informations... experiencing the outback with your own 4x4 is sooo awesome!
It's an experience you will never forget and it's worth to save some more money for doing a trip like that.