Once you decide on your destination, arranging some temporary accommodation for your arrival can be a good idea. A week or two in a hostel or Airbnb can help you find your feet before you arrange more permanent accommodation. Domain and Real Estate can be a great place to begin your search or Facebook groups such an Irish around Sydney / Melbourne / Brisbane / Perth, Poms in OZ / Perth / Sydney and local loop Facebook groups. If you'd prefer to just rent a room Flatmate Finders and roomates.com are a great way to find roomies.