Thinking about it some more, here's a couple more things you can do:
- You can use a , to give ita a choice of airlines. If for example only LO and LH flew to your home airport, you could make it "LO,LH f f+". Swap around the sequence on the way back. This would ensure you only get star alliance fares.
- Occasionally try adding more f's to your sequence because their search algorithm is lazy by design. It will not be very likely to find fares with 4 or 5 flights for example unless you force it to. Usually once I've found an interesting price I start pushing the boundaries using this technique.
- Figure out which fare classes do actually count for your segments. I'm assuming some "basic economy" fares would not be eligible. For example, I always pick "V" on Air Canada because it's the cheapest economy fare that will yield 100% miles internationally. You can guide ita towards those by using "f bc=v" in the "extension code" field for example, if you only want fares that are V.