Not cheap, but you will earn the most QF SC by flying with a QF code all the way, going via HKG or MNL with a OW partner, without a QF flight number, will see you earn not a lot of SC.
If you can, go Points + Pay, where you have a booking in J, and use the points to pay part of that J fare, while its not an economical usage of QF FF points, you will earn a larger number of QF SC by flying Australia to DXB with EK but with a QF flight number, in J with Point + Pay.
Don't tick the Classic Awards box, you earn no FF or SC points with that P + P.
People do say I talk a lot of bullpoop but its the fastest way to go towards QF SG.
I fly to NZ a lot, and have gotten QF SG by either flying only QF flight codes, either with Jetconnect, or with EK but ensuring I have a QF flight number.
Simpler and Fairer or Fairer and Simpler, have made SC earn on OW airlines, while being a QF FF member, earning SC is now a pittance.
Edit: SYD - DXB - LHR one way, flying with a QF flight number (EK metal), in J, earns you 24,800 QF FF points and 280 QF SC, double that when you come back, thats 49,600 QF FF points and 560 QF SC!
OR:
see what you could earn. If you're logged in you'll see your earn based on your tier status.
Silver
Compare with Flexible Business
11,700
Qantas
Points
135
Status
Credits
×SYD
QF
Business
To:Singapore
10,400Qantas Points
120Status Credits
Compare with Flexible Business
16,200
Qantas
Points
175
Status
Credits
×SIN
QF
Business
To:Helsinki
14,400Qantas Points
160Status Credits
Compare with First
2,012
Qantas
Points
90
Status
Credits
×HEL
AA
Business
To:London
1,725Qantas Points
60Status Credits
Total:
26,525Qantas Points
340Status Credits