It is shortest to take the west most (closest to the coast) road through Wanneroo (actually called Wanneroo road). It is an easy road to drive, however beware of driving it early or late. There are kangaroos in the area and they can really mess your day. They are more prevalent at night, early morning and dusk.
There are a few emus also, however they aren't as heavy, and don't cause as much damage.