1) Talk. Talk to your friends, talk to your enemies. When you don’t talk, people have no choice but to regard you as disinterested at best, and an enemy at worst. Frequently I have to assume that if you aren’t talking, you are plotting against me. That’s fine. If you want to plot against me, great, but talk to me anyway and convince me you’re my friend. That’s what this game is about. If you don’t talk, YOUR job plotting against me is hard.
2) Watch the whole board, not just your little corner. Once you have figured out your moves, who you are going to move against, check for possible potential friends or enemies once you make your move. For example, if you are Turkey and you plan on attacking Russia, check the situation out in the Russian north. Is England attacking up there? Great! Are Germany and France ganging up on England, meaning that Russia doesn’t have to worry about the north? Bad news! Russia can concentrate all his forces on defending against you. You may want to rethink your strategy.
3) Gaining centers in the spring means nothing if you can’t hold them in the fall. Think ahead to the fall.
4) Think ahead to the build turn and what your enemy will do. For example, you are Italy, and in the fall, you break your deal with France and enter Piedmont, planning to move to Mars next turn. But you didn’t count French units and SCs, and he builds an army in Piedmont, so you can’t get anywhere. So you lost your good ally and gained nothing from it.
5) If you attack, where will your enemy retreat to? Can he retreat behind your lines? To one of your supply centers?
6) If your unit gets defeated, consider disbanding, rather than retreating. For example, if you are Russia, and you just got defeated in Munich, but its fall, and you have 6 units and 6 supply centers. You could retreat to Ruhr, or you could disband and build a new unit in Sevastopol. Which makes more sense?
7) Think ahead! Not just one turn, but 1 year, 2 years, and more. For example, you have a great ally, and you currently have 14 units and he has 10. So you think you are winning the game. So figure out how you can win. Are there 4 centers you can take? Or has your ally staked claim to the rest of the board, so the only way you can win is fight your ally? And if you are Austria and you have joined with Russia in beating up Turkey, what happens when Turkey is dead? Have you left yourself open?
8) Learn to adapt. Your enemy one turn might be your friend the next, as long as it in your mutual interest. Don’t stick with a plan that isn’t working.
9) Fighting to gain that extra SC, but having no where to build sucks.