Start with a country in the middle of the map
A first guess in a central place such as Egypt, India or Brazil is rarely more than about half the world away, and its distance already rules out whole continents. A guess on the edge of the map tells you less.
Follow the arrows, then triangulate
The arrow points from your guess toward the secret country. Two guesses from different directions give two distances and two arrows, and the secret country lies where those lines cross. Aim your second guess well away from the first.
Use the distance, not just the percentage
Proximity is the distance squeezed into one number, so the kilometres are more precise. Under about 1,500 km you are usually in the same region; under 500 km you are probably next door.
Remember how countries are measured
Distances run between the middle of each country, so large countries such as Russia, Canada and the United States can be farther or nearer than their borders suggest. Only listed countries are accepted, and there is no timer, so think before each guess.