This is more a micro suggestion than a macro suggestion, but a method of playing the Axis that I’ve picked up from Stalingradski on this site, is to purchase a naval unit and an air unit every turn as Germany, even as you advance on the USSR. The longer your Atlantic Wall holds through Naval and Aerial Supremacy, the longer you have to overwhelm the Soviets with superior numbers. The idea being that if you’re making a mad dash to Moscow with Mechs and Tanks, and the Soviets are able to trade Infantry for your pricier pieces, you’re much more at the mercy of a couple of bad dice. Whereas if you can delay an Allied landing in western Europe or north Africa for a few turns, you not only ensure much much better odds of capturing Moscow because of the extra cheap Infantry you can get to the front in time, but you increase the chances that you’ll be able to claim Cairo soon thereafter.
Allowing the Allies to get a foothold in Europe or north Africa while the game is still undecided makes your life a lot harder. The ounce of prevention keeps Italy (Germany’s soft underbelly) alive and allows you to fight a one-front war against an enemy that you should be able to economically overwhelm. Granted, it’s not an easy task in the game (mirroring history - that’s a LOT of coastline to defend), but it’s easier to defend with navy supported by air than it is to keep enough forces to defend multiple locations on land.
You use G1 to wipe out as much UK navy as possible. Take a look at some sample forum games for some standard opening sequences - you don’t have enough resources for all your objectives, but you should be able to get him down to just one seazone of ships. With your due attention on G1, and if you can keep the Americans out of the war until after you’ve had 4 German turns, you should get the upper hand in the Atlantic and be able to prevent the UK from putting a navy together until at least then. If you don’t take care of business with the UK navy early, he’s able to add to his forces or hide them until they can merge with the Americans, and you’ve lost the Battle of the Atlantic – at that point it 's only a matter of time until the Allies are landing and making a two or three front war for you. It severely limits your options, makes taking Moscow extremely time-dependent (and a one-shot deal), and makes you need to commit resources reactively instead of proactively.
You don’t want to have to buy what the Allied player wants you to buy, you want to make him buy what you want him to buy. That’s the reason that G1 is so scripted. It all works together: The 1 Carrier and 2 Transport buy, keeping the Soviets and the Americans out of the war, attacking UK navy, the land grabs in Europe to boost IPCs so that you can threaten to purchase 9-10 transports on G2 – it all makes the Allies reactive. He wants to neuter Italy with a UK1 Taranto raid, make a Mech purchase for South Africa, and drop a Cairo IC – you put him in a position that if he does it, then he loses (because if you don’t do that, and he does do it, and you don’t make him pay, then you have no chance to win on the Europe map).