Given that in single-player you can conquer the world as Germany if you have both eyes shut and just randomly click on the screen, I would guess in multi-player one eye open and random clicking on the screen would probably win a 1 on 1 game
If you are playing Germany and you have human players in the Soviet Union and 2 Allied majors then I would suggest that you spend all of the pre-war period building up your army, then wait until after you conquer Poland to attack France (just like in history). This will probably result in the French player having time to move all his units to his front line with you. Blitz through one section of his line and capture Paris with infantry while cutting the supply of the Maginot line with your tanks. A human France probably won't accept Vichy, but if he does, all you need to do is fortify your beaches and leave a few German divisions in France while you prepare for war on the Soviet Union. If the human France doesn't accept Vichy, then use fast units to capture the unprotected sections of France (the human will probably have almost all his troops on the front-line, which you have previously encircled and denied supply). Start mass tac-bombing the maginot line, and only attack when from your tac-bombing you know that the French troops have almost no organisation. Roll up their entire line in this fashion.
The UK will not be able to build large a enough army to threaten you in Western Europe for years. Unless you have a human US, you can probably just fortify the beaches, and leave some infantry there and in key points, creating an Atlantic Wall.
Deal with the Soviet Union. Unless there is a human US, the Allies stand a very poor chance of being able to threaten you in Western Europe. The Soviet player will probably accept the Bitter Peace because it really isn't too bad a deal for them, it will still leave them with a reasonable amount of ICs especially if they moved their industry to Siberia and upgraded their ICs from the start. Once the Soviets accept Bitter Peace, you should be able to bring most of your armies back from the East to mount an invasion of the UK or just to defend yourself until the end of the game.
Another piece of advice - contribute to Italy's effort in North Africa with whatever spare armies you have. The longer the British are tied up in North Africa, the longer you have before you have to deal with them invading you, since their manpower will probably preclude them from being able to build large armies for both theatres.
