These are usually gone in the first few moves, so you'll have to take the rest of the centers from other powers. The deal is that you can't take them alone. You'll have to cooperate with some of the other players to get what you want. The trouble is that they want the same thing you do. The real appeal of the game is in the fine balancing act between amity and treachery that goes on among the players.
Diplomacy is played entirely without dice or any other luck based rules.
But the uncertainty in the game is purely a product of human behavior. In other words, it comes to down to who you can trust. No one can ever be counted on to do what they say they're going to do so the shrewd Diplomatist is also a cunning judge of character. Although there are definitely strategic elements that can't be ignored, the best Diplomacy players are those who are the smoothest talkers. The close up views will help you formulate your strategy.