So I did take advantage of my break to really put some time into learning Gary Grigsby's War in the East.
What really killed me was supply - I'd regularly outrun supply, especially with my panzer and motorized divisions - and have my offensive grind to a halt while I found ways to force fuel back up to the front.
Looking at some AARs helped, but so often they were in Beginner mode and I started in Intermediate, so they'd manage to break through the Soviets much more easily and supply much more effectively.
But I did find a simple but useful guide to supply here:
War in the East Supply Basics
It's very basic, but that's what I needed - something that just told me what to do and where to look.
Armed with that, I fired up a scenario I'd been playing - Road to Leningrad - and tried what I knew. I started with my panzers already out of fuel, and did what I could to rescue the situation. I managed, but the loss of momentum (and some other mistakes later on with support and unit distribution) kept me from taking more than half of Leningrad itself and left with an Axis Minor Victory instead of the Major Victory I'd hoped for. Well, that and not being able to cut off supply to the Soviets in the city, which I'd thought I'd done enough to effect but apparently had not.
The next time I played a bit, I was able to keep my fuel-sucking panzers in fuel the entire time. What a difference that made - I haven't finished that playthrough, but I'm much more solid.
Now to learn administrative tasks, like creating units (support and otherwise), replacing officers, creating new formations, and reassigning units to new HQs. Some of that I've done in play, but mostly ad hoc.
Fun game. Hard, but fun.