Official ticket sales are the best option, available through official ticket outlets. More information from the official website.
Any search online for "Australian Open Tickets' will come up with many websites selling tickets, and there is no sure way of knowing which of these resellers are reputable. If you were unable to get a ticket through official sources, and you are desperate and willing to spend a lot of money, these may be the only option available to you.
- More about the Australian Open Tennis