Firstly, lets discuss what premium numbers are. Premium or Smart Numbers are 1300, 13 or 1800 numbers which have a particular pattern of numbers or the numbers spell a word. The ACMA make this decision.
Smart numbers have a public website with a public Auction process where you can search for numbers and place bid’s on numbers. The process will require you to register ($42 once off).
The Auction process takes a few weeks and the auction start dates and closing dates are clearly listed on there website.
There really is very little you can do. First test is to call the number and see if its connected. If it is connected you have zero chance of getting it (unless you contact the owner and convince them to sell it to you).
If it is disconnected, again as above contact the owner of the number and they may lease it to you, or sell it to you outright.