New long campaign player needs tips.

[Roman]

Some time ago I do not do a long campaign with Germany. But I remember the headache comes when faced with France. Their tanks are very hard. But most of the battles are in wooded terrain, the infantry G. Ladung does a good job. Also jpz1 and 88.
In Poland you have to reach with your tanks and infantry. The 37 mm anti-tank kill all tanks Poles, but you must update to 88 mm or jpz1 when you fight with France. Also remember that your tanks are not Tiger at 39. Do not send them to their death.
It's just a small comment about tanks.

[Nitro Cruiser]

Something else to consider, increase the map size a little to give your support units a little breathing room, but not too much or you'll spend a number of turns just getting to the front.

Speed is a great asset of the German forces, us it to your advantage. I like to buy a couple of motorcycle units. There is one that has two MMG's with it. It is great for zooming ahead, dropping off the MMG's into position and grabbing victory hexes. The MMG's can even put a hurting on British Dingo's and other armored cars. At the very least they tie down enemy forces, while your slower armor can catch up.