Take a look at my game, as Russia:
gameID=38295#gamePanel
One of the best things to do in diplomacy is play people off against each other. In the east, I worked with Turkey to destroy Austria, but only after I got Italy to attack Austria. So while Austria destroys Italy we destroy Austria.
In the West, I inserted myself into an anglo/french vs german fight, after England attacked me. Instead of giving up, like some players are apt to do (cough, england, cough) I fought back and worked with a former enemy (france) to destroy germany.
So, now you can see that I'm about to win, as Germany, Austria, and Italy are all basically gone. While France and Turkey are too weak to oppose me.