|Capture other players|
When you eliminate another player by conquering their last country, you take all of their cards.
All things being equal, it's better to capture players with more cards than players with fewer cards. Similarly, it's better to capture a player just before they turn in cards rather than just after they turn in cards.
If you take another player's cards and get five or more, you must turn in cards in the middle of your turn. If you have two cards, you should try to eliminate a player who has three or more cards. If you have four cards and you capture a player with five cards, you can turn in three sets at once!
If you wait until the other players all have lots of cards, you can eliminate several players in a row by using each player's cards to conquer the next! It's possible to sweep across the board in one turn this way.