Africa buys the Germans nothing. They lack the navy to support operations there. Supporting the Italians there is nothing but a distraction. Trying to use the Middle East as an oil source will be hard. This puts them on a head on collision course with the US once again (the US is the leading developer of what Middle Eastern oil sources that are available).
On that note, I would add that keeping the US out of the war (including Lend-Lease) should have been a major German strategic goal. The US is the leading nation in terms of capacity to crush Germany. The Soviets are a tough enough nut on their own. With the US thrown into the mix the Germans are finished.
The Germans could have just made better use of the oil and coal they already had. Coal gassification and synthetic fuels could have been greatly expanded on local resources rather than relying on a tenious campaign in a distant land trying to capture these resources.
On Poland, if the Germans could have managed it or, planned for it, they should have taken the whole country before allowing the Soviets to occupy about half of it. This places them almost 300 miles closer to Moscow when they do jump off. Again, better strategic planning.