Re-iterating what others have said, strategy rule #1 is to grab the rock-bottom deal (or even the mistake fare, if you're really lucky) and then figure out the reason to go there.

Realize that a lot of the best-value mile-earning trips on your own dime might be driven by unknowable factors like fare-sale patterns or even fare mistakes. Fare mistakes have been responsible for trips to places like Barbados, Acapulco and Rome for me in recent years. Fare sales are driven by competition and may favor the same group of cities.

Used to be there were also occasionally some eye-popping mileage sales. My all-time faves included 20K RT to Dusseldorf, 25K to Hong Kong, and 40K to Bangkok.

Which gets to rule #2...Be prepared to hear old-timers tell you how things used to be a lot better and how you're working a lot harder now for less bennies. You got in at least 10 years too late. Oh, well, better late than never.