EFFECTIVE GERMAN STRATEGY, ROUND BY ROUND:
G1 = Buy 13 infantry. Transport 2 infantry to Norway. Take nothing out of Western Europe (on round 2 move WE tanks out). Move in WE 1 G infantry, 1 SE infantry. Take back lost territories in Europe, and Leningrad/Karelia, if possible. Attack Russian sub with Norway fighter if you don't need it elsewhere. Place 10 INF in G and 3 in SE. ALT G1 BUY: Buy 10 infantry + 2 tanks or 1 fighter.
G2 = Buy 5 tanks, 1 fighter. You'll use the 13 infantry bought to 1) beef up WE, beef up Norway by way of your G transport (if not dead) and to stop any Russian advance dead in its tracks, so that on round 3, you can start beating them back.
G3+ = Pick one of the above buys, as needed, or a simple variant, such as one of these two: 10 infantry, 2 tanks, OR, 4 tanks, 2 infantry, 1 fighter.
Do not lose Norway (if you do, take and hold Karelia)! Always regain any 3+ IPC territories lost immediately. If you lose some 2 IPC territories, either take them back or make up for them as best you can by taking Russian territories (Karelia/Archangel) or Middle Eastern/African territories. Do not let your income drop below 35 IPCs!
While you should probably make a token attempt to take Africa (and you should always crush the UK battleship on G1 with your battleship, sub and WE fighter, + transport loaded with tank and infantry from SE). If you are playing with Atlantic Wall NA, put the transport dudes into Algeria and move all Afrika Korp forces into Algeria with them. Otherwise, in a normal rules game, I suggest one of two courses of action: 1) Use transported units in Amphib vs. Gibraltar (particularly against experienced opponents) to prevent Allies from landing planes there, or 2) put the transported dudes into Gibraltar for safekeeping (you brought the transport along for safety from the UK destroyer, which will probably leave for the Indian Ocean on UK1) and take everyone out of Algeria to reinforce Libya. On G2, you will transport Gibraltar forces and attack with BB Anglo-Egypt (or Algeria, if you prefer, but since this strategy assumes you will not hold Africa and are just after some quick IPCs, why bother to fight USA landing forces?). Be careful to reinforce SE during non-combat and/or place units phases, as an astute USA player may take advantage of this to land token force in SE if you have not destroyed his Atlantic transports (which you may not be able to do as your planes are probably in the east for protection against Russian aggression).
At this stage (G2), if America still has transports in the Atlantic, I recommend moving all fighters to WE to shut down an early D-Day and then use those fighters to blast any nearby transports every turn. That is one reason why buying 5 tanks + 1 fighter is a good strategy vs. Russia and the pesky UK/USA (the other reason is you can use them vs. Russia quicker and the fighters give you more flexibility). As long as you still have your Mediterranean transport, you must use it to either support attacks on the lower Eastern Front or else make easy token "harrassment" conquests of empty territories along the middle East/Africa (if the USA screws up badly enough, send it to conquer Brazil for fun, then attack Western/Southern Africa, staying one step ahead of Allied opposition). Remember that the UK fleet will be unable to move through the Suez Canal unless they hold both Anglo-Egypt AND Trans-Jordan, so try to conquer and hold one or the other. You do NOT want the UK's Indian fleet disengaging from Japan and storming through the southern Reichlands to link up with the UK fleet! They should not do this if Japan is playing its part properly, but you never know...
You want the Caucusus IC ASAP, but if it's obviously not forthcoming, try swinging those relentless panzer battalions of yours northward through Karelia/Archangel toward Moscow, thus forcing Russia to divert her attention and hopefully, end her westward attacks in favor of a more defensive strategy. If Russia is on the defensive, they cannot be on the offensive!
Overall German Strategy: Do not let the UK/USA distract you overly much from attacking Russia. You must keep the pressure on the Soviets if you are to win, while holding onto as much of your starting territories as you can (and whatever else you can grab). A protracted African campaign diverts your attention and resources from what truly matters: conquering Russia!
MORE COMPILED A&A STRATEGIES
http://boards.avalonhill.com/showthread.php?t=2495
OPERATION: SEA LION
Another ALT G1 buy is to get an AC + 3 transports and threaten the UK with "Operation: Sea Lion" on G2. You will likely never pull off Sea Lion, however, and shouldn't attempt it unless the UK is lightly defended with little to no oposin navy. The "threat" should provoke an overreaction by UK/USA to defend UK instead of buying an IC in India, thus helping Japan out a bit. However, this strategy can backfire, in that your defense of the Reich's land territories will suffer and your eastern aggression will be blunted for several rounds. I'm not sure about this strategy, having only tried it once with mixed results, and never even attempted Sea Lion (though my oponent never knew for sure I wouldn't try, LOL).
More on Sea Lion strategy here:
http://boards.avalonhill.com/showthread.php?t=1180