In Plague Inc. for the Android & iOS (iPhone, iPad, iPod Touch, etc.), Greenland is usually one of the last countries to get infected, and can be quite a pain in the ass sometimes.
The only real way into Greenland is by their Seaport, and they’re nearly always infected by a ship coming from Norway.
Greenland and Norway are both cold regions, so purchasing the Cold abilities on the Abilities page is important to not only infect these northern countries, but to also make your plague spread faster in these countries as well. In nearly every game I play, I end up purchasing both Cold abilities for this reason.
Another tip to increase the infectivity in Greenland once it’s infected is to purchase the Bird and Livestock transmissions, since Greenland is very sparsely populated.
Check out my other Plague Inc. articles if you need more help in the game.