The basic strategy is actually pretty easy, IMO. Buy tickets when they are cheap and see the world.

There are very few destinations in the world that I would not actually want to go so if a cheap fare comes up that I can reasonably find dates that work for me, I book it. I didn't go in to the year explicitly planning on having trips booked to Belgium/Luxembourg/London, Peru, Panama, Rome, Belize and Denmark/Norway. But the fares came along for those destinations and I jumped at each one.