Buy all artillery round 1 - 3 Stalingrad, 3 Ukraine, 1 Moscow
Buy all artillery round 2 - Placement depends on G2 or G3 DOW
Round 3+ buy 9 Inf + 1 Ftr
When you can no longer afford that (which will eventually happen), spend the 30 IPC for 9 Inf on Moscow, and anything you can afford that can beat the Germans to Moscow that you can place in Stalingrad (2 Mech > 1 Armor).
Continue on this route until Germany attacks Moscow directly.
I prefer the additional Artillery on R2 in the situation I can counter attack on R3 if there was a G2 DOW. Notably if Germany races too far forward on G4, I’m going to want that Artillery available to cut deep into the German Armor on R4 and potentially stall the advance.
Learn the art of strafing. Example:
Germans take EPoland with their big stack. You had stacked everything in Belarus / WUkraine. You retreat backwards to Bryansk, consolidating your stack.
Next turn, the Germans move their big stack to Belarus, but they blitz a single tank through W.Ukraine to Ukraine, and another tank through Baltic States to Novgorod.
You being next to Ukraine with your stack, can send in 2 Inf, 2 Ftr and 1 Tac to reclaim Ukraine from Germany. You figure there is a 50-50 chance of losing 1 Inf, so you’ll strand the lone surviving Inf in Ukraine while your Ftr fly back to Moscow and join your stack that is retreating there.
You’ve effectively denied the Germans the use of Ukraine next turn for 6 IPC.
Just remember, trying to leave blocking Inf in 1 IPC territories is a bad trade for the Russians. You give up 3 IPC and certain death of the unit to deny Germany a 1 IPC territory you will lose regardless if the Inf was there or not.
It is better to strafe the exploratory blitzing Germans where possible.
In a last ditch effort, you can block with an Inf if you are caught out of position - just beware an Italian “can-opener” where the Italians blitz an armor forward, supported by their bomber to clear that Inf out for the Germans to blitz and ruin your day.
In an entirely worst case scenario, if you have no way to save yourself, you can spend the IPC to place an AB in a location to block a blitz that would ruin everything. Blitzing units cannot move past infrastructure they captured that turn. So, in theory you can place an AB on Smolensk and keep your Russian stack on Bryansk to prevent the Germans from blitzing into an undefended Moscow.
It could be worth it if you had Ukraine under your control, the German stack was in Novgorod, with nothing protecting the soft underbelly in Romania and Germany just purchased boats and planes so there was no new ground units coming out of Berlin.
You could do some economic damage spending 18 IPC on 3 Arm in Ukraine, blitzing them to Poland and then spreading out to Bulgaria, Albania and Slovakia on the next turn.
Assuming you lost all 4 territories the turn after you claimed all 4, you could realistically have gained 15 IPC from NO’s (Romania twice), 6 from Romania, 3 from Slovakia, 1 from Bulgaria and 1 from Albania for a grand total of 26 IPC that cost you 18 IPC and on the “Annoyance Factor Scale”, you went off the charts in aggravating the German / Italian players while possibly causing serious problems in their defense of Europe from Allied incursions.
That won’t always be there, but it is something to keep your eyes open for.
I also have an opponent that consistently positions to attack Finland the moment Germany starts the war with the intention of taking Finland and Norway to collect 11 IPC / round until Germany diverts resources to correct that problem. This R1 purchase includes 1 Arm, 1 Mech, 1 Art placed in Leningrad. You can look through that minigame he plays there, but the Annoyance Factor Scale is pretty high on the Russians taking Finland and Norway very early in the march to Moscow. In short, its +11 IPC for Russia, -10 IPC for Germany until they correct it. You spent 14 IPC to do it, trade out around 12 IPC of units to accomplish it, but its a 21 IPC Economic swing as long as it is in effect, so it pays for itself immediately. Then costs even more IPC for Germany to correct the problem - which means less units headed to Moscow. Oh… and have fun correcting it with 4 UK Ftr sitting on top of 6+ Russian units in Norway.