Familiarity with qantas.com and its award booking system
Limitations to the itinerary that can be booked on the above
Pure availability of flights
The Multi-Destination option on the web site means that you can be fairly flexible about your itinerary, though this flexibility has come about through leg-by-leg charging so the required points are higher. If it can't do what you want then the only option is to call Qantas and cop the assisted booking fee.
But availability is the key, and although there are some automated tools that will alert you when segments become available, I find the most effective method (for the desperate) is to log in every waking hour. It's either that or travel to un-popular destinations at un-popular times.
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- Book early
- Similar to less traveled routes, consider less popular flights, eg Day flights to Japan instead of night
- Look at days where the is a double up of flights for example 3 days a week to NRT there is 2 flights that leave 5 mins apart.
I generally have had no issues finding flights if booking in advance, 2 weeks before you can just about forget about it.