Which way will you go? It's a long way whichever road you take.
Make sure you have basic spares such as fan belts, top and bottom hoses and emergency windscreen. Carry at least 10 litres of drinking water and have some nibbles to keep you for a couple of days if you get stuck. If going to take the smaller roads, be aware that many in WA that look like highways on the map are pretty ordinary. Make sure the jack works so you can change a flat. A second spare wheel, a small shovel and a couple of oat bags can save tears if driving rough.
Some fantastic scenery along the way so try to enjoy it rather than just blasting through. Note that wandering cattle, donkeys, horses and kangaroos are some of the hazards if driving at speed. Take a digital camera with you and record your time up there because it will stay with you forever.
Enjoy
Kaz