I gave some example in my trip.
Some may not be applicable.

Before devalution, one can do
South pacific to Japan in business for 20000 UA miles
(it now costs 30000 miles)
I did JFK- LIM - SCL (stop) - IPC for 40000 BA miles in J under the old rules.

I have a trip using US air miles from Asia to Europe for 30000 miles in J. You just need to know all the rules and deals and combining them.

You have come up with a place you want to go, then find a program to make it work. I start from the rules of all the programs and find the best deal, then combine to make a trip.