Well, here is one strategy I’ve used in the past that may help with Africa (RR, no bid). You won’t be able to keep Africa with this, but you might have a chance to at least take it for a turn or two.
On G1, sink the UK Navy in the North Sea as usual, but do not use the Baltic sea transport as fodder. Once all Allied ships there are sunk, take the Baltic sea transport and move either the Norway tank (my preference)or two Norway infantry to Morocco. Also land at least one of your fighters there as well. Instead of taking Egypt, simply move two infantry into Libya.
This sets you up fairly well for G2 in the following ways
The transport blocks the UK/US from an easy run through this area. The UK will sink this, but this will divert forces from other uses (i.e. if they use fighters, they will not be able to land in Karelia on UK1 - possibly making a G2 assualt there feasable). Probably the UK will also sink the German Med fleet (its really inevitable).
The extra forces in Morocco will delay UK/US forces from landing in Africa on round 1.
On G2, use all available forces to take Egypt. The extra tank and fighter(s) will help defeat any forces that may have been moved to Egypt on UK1 . You should also consider using the bomber as well if they have done so. Now the Allies either won’t have sufficient forces to effectively counter-attack, or you will have sufficient forces in Egypt to make a counter difficult at best.
On G3 and onward, you then use these forces to fight north-south. You should be able to reach S. Africa then retreat back to Egpyt to defend that against the Allies. Here you are just scrambling to keep as much as Africa in German hands as long as you can. The Allies are able to take it all back, but now they must devote more resources to do so. Also, it is possible for Japan to bring in reinforcements to help Germany, but I never do so since the Allies are closer to Africa than Japan and the Japanese forces are better used elsewhere, IMO. At some point you should probably conceed Africa and move the fighter back to the relative safety of Europe.
There are problems for the Germans with this (loss of a defensive fighter in Europe for a few turns, Norway is weakened, and the odds for this working as stated are not exactly a slam dunk) but you should try it to see how it works for you.