From: Kinmel bay
I guess there is no real right way to use the cards, every player is building their own strategies; it also depends on the scenario.
I dont think there are any AARs that specifically give tips on when and how to use cards, they are more mentioned in passing. Here is some stuff that I do, but like I say, others will have different strategies.
High Command cards:
As Soviets the two I sue are the ambition cards and the fortification cards. I dont really end up having much left to use for anything else, especially not in the early game. It is difficult picking where to use fortification cards, but they are useful to have. The ambition card has a two fold purpose, they help to avoid dismissal and also give an immediate one point prestige point. It doesnt seem like much, but if you do manage to survive the early game they can hopefully build up - it is always a bit of a gamble though as you may get given objectives that the Germans are about to play.
For the Germans I've only ever really used the ambition card and mainly during the Uranus scenario to stave off dismissal. The avoid cards must be useful but I've never managed to get that far as the Germans in any of my games!
Everybody will have their own opinion on which cards to use. But as Germans I generally start off by playing at least one rail card, after that I seem to always spend everything on fighters to try and win the air battle. Next on the list is infantry followed by things like tanks and trucks which are generally rare luxuries. As for the Soviets, very similar. They have more rail capacity, so I may not spend points on that, but again I'd probably concentrate on fighters and infantry. Occasionally I may play an AA or engineer card, especially early in the game. I like to have one engineer units sat at most of the strategic bridge crossing points and AA units at some of the most vulnerable, just to discourage the German player from their bridge bombing campaign. I generally will create a few extra engineer units early on in the game and play an engineer card to start them off.
OKH/Stavka and Army (German) and Front (Soviet) cards
These all depend on what generals you have where and as you move down the levels of command there are more variations. For OKH, whilst Halder is still in the game I reckon it is worth using the emergency troops cards. Although not frontline troops it does help to have more units to help fight partisans and guard ports. With Stavka I always save up and use the support card and I've found it seems to work better when given to an individual army rather than a front command. When an army is retreating or counter attacking those extra readiness points are really useful and can give the units a bit more defensive value or enable them to have another turn of counter attacking.
For the German army commands it really is a case of saving up and using the best ones for the situation. The best ones are the freedom of action for a Corps in my opinion as they give a nice mixture of attack and movement points. When in a defensive situation the entrenchment card is useful or the emergency troops card. You'll have to look through and get to know each general's abilities and work out where you want them. For instance a lot of players will swap Paulus out early, yet he is a useful defensive general to have. In my latest Uranus campaign he was flown out of the Stalingrad pocket and is doing sterling duty as the commander of 6th Army.
For the Soviets you are quite limited in the early game as to which generals are useful as front commands. To my mind I like to have generals with entrenchment abilities again, but you will be limited with prestige and may struggle to get more than a couple of these into front commands early on. With the others I am more concerned with making sure they have decent organisational abilities rather than decent cards.
German Corps and Soviet Armies
For German corp commanders the game gets really interesting and I'm sure each player will have their favourites. Again it is a case of trying to get the right generals in the right place. For quieter parts of the line I like to have generals with good defensive abilities and also have the experience and conduct exercises card. These can be really useful in bringing up experience for units 'resting' on quieter parts of the front. You need to have your good panzer generals available in your main armoured spearhead units. My favourite is the initiative card which gives nice rounded bonuses to an attack unit. Also dont discount the usefulness of the speed card and the care card for attacking units. The speed card is useful for following a collapsing Soviet defence and giving your spearhead units more than one decent attack against retreating units. Another under rated card is the care for your troops cards. It gives useful morale boost but also gives a boost in readiness, again I find this useful for units involved in attacking tough parts of the line and enabling them to recover readiness to deal with counter attacks or to be able to attack with full force again the next turn.
For the Soviets things are again limited in the early game, your main concern should be on getting generals in place with decent organisational abilities. Having said that, depending on who turns up in the officer pool there are a couple of useful offices around. If you're lucky enough to have units in quiet places of the front a couple of the generals do have the conduct exercises card. Also a couple have the entrenchment card which I generally try and use in the Rostov area to slow down the German breakthrough.
I hope all that helps, the cards do get some getting used to. One card I am never going to use again is the gamble card, I have had it fail on me on three occasions at crucial points in the game. As for AARs, Reconvert seems to put quite a few references in his and the AAR that was put up about the linked campaign has quite a few references on using the cards.
The thing is you need to experiment a bit with how to get the most use out of them and I'm sure other players use entirely different tactics to mine.