1. Initiate as few attacks as possible
2. Let your enemies break up each other’s continents;
3. Take only one country per turn
The problem is that it doesn't explain which country to take, and how to attack without being attacked -- which is what makes the game difficult.
But, then, the article suggests something new (at least for me):
1. Find a way to grow in strength by taking lots of countries (but not taking a whole continent)
2. Make sure you get lots of cards for bonus armies
If this is a good strategy, I have always played it wrong -- because I've always tried to take whole continents.