The Internet offers many travel websites to compare prices from various airlines. Some provide charts of the most affordable dates, and they all offer the option of signing up for alerts via email concerning the costs of the tickets to Australia. Sites worth noting are Kayak.com, Orbitz.com and Expedia.com. A newer site, Bing.com, has interactive features that allow you to explore a variety of travel dates.
After researching travel options and finding a flight that meets your needs, carefully read the rules and regulations. It is important to know what your options are concerning penalties if your trip must be changed or canceled.
Purchase the ticket.
Research passport and visa requirements at least a couple weeks before your trip, and comply with any actions required.