its very hard for sure in this mod i am grinding it few past days myself.

My advice so far:
1. Lower the difficulty level: regular gives flat attack and speed bonus to enemy troops, which is not fair imho. For the best experience I suggest go with Recruit (and if you want, give USSR 1 point of custom bonus, not more)
2. 150 divisions is the bare minimum to invade USSR, since the front will get huge while you advance deep in enemy territory. Try to aim for 200, even if they are somewhat "reserve" divisions.
3. Set up two panzer armies. The key in beating the russians is to encircle as many enemy divisions as possible while the barbarossa bonus is active. Do not expect to win with simple WW1 front tactics, you need real blitzkrieg.
4. Fighters and CAS are fundamental to de-org enemy troops and let you wreck havoc.
5. Do not forget that the finnish front is weaker than the main front, so try to secure Murmansk and all the land up to Leningrad.
6. Cut the allies lend-lease convoy raiding the northern seas. If the convoys reach USSR they become unstoppable.
7. Use logistic company, extra logistic and small logistic on every single division you have. The infrastructure in Russia is bad, so you need to drop down your division supply weight at the front.
8. Check the terrain before you move your panzers: marsh will wreck your tanks hard, mountains, hills and forest are not good. Try to encircle in the plains.
9. Use 2 field marshals with infantry to cover the entire front, then 1 field marshal for generals with tanks or special troops (like Waffen SS) for breakthrough.
10. Attack with everything you have at the start and do not stop, no matter what. Strat bomb if you need, just do not stop the offensive. Once your bonus are gone, and the russian malus are over, you are toast.
11. Do not forget that you can take control of your puppet's troops. They provide a lot of bodies to hold the gigantic frontline and can prove critical to avoid your front crumble.
Hope this helps.

Thanks for that. I will try your suggestions. I am a bit suspect on the 200 divisions, though. I can't even get 150 to move. Most of the other stuff I already attempt to do, except for the lower the difficulty settings. Will try in a new game. Again, thank you for the detailed help.

I will add to that:
12. Always micro your tanks, and even your infantry whenever possibile. Try to close as many pockets as possibile and wipe them out as quickly as you can.
13. Whenever you conquest new regions, build immediately max infastructure everywhere. Do this and your army will have no difficult to fill the frontline (this what Germany tried to do in real life)

Yes, 200 divisions are a lot, but consider this: when you invade Russia you will notice that the main front will kinda split into two trajectories: one that goes straight to Moscow and the other one that from Romania goes toward Stalingrad and the Caucasus oil fields. They are both important, but Italian and Romanian troops will be placed only in this second front. So you place your main armies in your german front, and send the "reserve" army to help romanians and italians not to lose ground. For this a simple light infantry or even garrison division army is enough, maybe with a couple of tanks for small breakthroughs.

So you have it: your Wehrmacht at your front pushing toward Leningrad and Moscow, and the reserve army helping Romania and Italy fight in the south.

I know it seems bad to lower the difficulty setting but I don't like flat combat bonuses to AI troops. Economic and other stuff is ok, but troops should be even.

Well, my first attempt at this resulted in disaster. I thought I had done everything right all the way through summer, 1941. Then, I guess it was about October '41, I noticed a huge gap in my front west of Minsk. Soviets were pouring through. I pretty much gave up shortly after. I turned the game to its highest speed and just sat back & watched except for keeping NFs & research as up-to-date as I could. Romania switched sides and it was all over. Soviets took over Finland and advanced through Poland and into German homelands. My entire Army Group Center was surrounded in western Russia. Eventually, it came down to a mountain army up in Norway and a dozen divisions in France. The crazy thing was my war support was at 100% and my stability was still over 60%. I stopped watching in late '43. Romania had taken over Hungary and Bulgaria, plus my previously taken Yugoslavia & Greece. Russia had everything else except a bit of Scandinavia that was in Great Britain's control. I don't think the mod is working correctly with the HOI beta. Some odd things happened. Plus, I really suck at this game!! :-( Gonna give it a rest for a spell.

Da

have you tried building infrastructure? I know it sounds obvious but tech up as much as you can on all infrastructure / road / rail techs before invasion as well as construction and build as you advance. If you aren't building up infrastructure the invasion is literally impossible with this mod or black ice.

I keep infrastructure as current as possible. Have not built as I go in Russian territory, though. I'll try that one of these days. Thanks for the info.

Checked in on discussions, as a dev and one of the best multiplayer players on Total War I could give some minor tips:

A 4 medium 4 mechanized 3 light spg 1 heavy at is a pretty good template before barbarossa, a more experimental approach (more likely to be nerfed) would be 4 medium 4 mechanized 3 Heavy Art 1 Heavy AT

You should (with correct production management) get up to 40 of those divisions by barbarossa, 12 by Poland, 24 by France

Another thing is I usually go medium bombers, no cas, cause i use the bombers for strat bombing the maginot and cas work, if you strat bomb the maginot you could likely go right through it.

Make sure to put 3 logistic companies: 1 extra 1 logistic 1 small logistic and a motorized logistic company if it's for tanks.

Don't put your infantry in romania! The Romanian AI will likely eat up your supply, let the italians, romanians and hungarians deal with the south.

Encircle and destroy before winter, you don't want to have the enemy soviet have 300 divisions in winter, otherwise you're gonna likely stall out the game for long or lose. You might wanna consider declaring war as early as May or April if that fits your aggressive playstyle.

Use The "Blitzkrieg" ability on your tank generals to get the extra armor division attack buffs that you will most likely need to make big breakthroughs.

Another strat is to go 3 light tanks and 1 medium 4 mechanized and 1 stug 2 light spg and 1 heavy at, very fast, quite effective tanks that are meant to overrun the enemy before the onset of winter and before you get your heavies. Important thing to note is after recent balance changes, you will NOT have heavies before Soviet, dunno bout AI.

Last game i tried with the Heavy Art template on tanks i got to moscow by August 41 and the other templates were by November.

"You might wanna consider declaring war as early as May or April if that fits your aggressive playstyle." - Ha Ha - I am the George McClennan of Total War. Great suggestions, though. Wondering - how do you get so many mechanized divisions when mechanized vehicles aren't available [without penalty] before 1940? I do put 3 logistic companies in all my front line divisions, and I have learned to leave the Romanian border to the Romanians to deal with. I have thought I may be building too many planes and have toyed with the idea of using only fighters and CAS. Never considering using medium bombers, instead, I'll tell you, I think my main problem is inability to micromanage all my frontline divisions. To my old eyes, it all becomes a jumbled mess. I try to use the battle planner as best I can .... but, I end up stagnating by the Latvia/Lithuanian border/Minsk/Kiev [short of, usually] axis. Some great food for thought, BezMemow. Thank you!

You get a penalty reduction for mechanized from the "Improve Offensive Capabilities" focus or something along those lines, this way you start researching it in 39 and you get it by poland, mechanized doesnt cost much in terms of production so you will get a lot of it, of course, before that you have motorized instead and u steadily replace them with mechanized. If micromanaging is the problem (which it usually is, i tried using the battleplanner only it doesnt work out really that well), try going speed 3, i usually go speed 4/5 and im fine but i am youngster little covid-19 fashion boy so reaction times real quick

@ BezMemow To make 40 armor divisions by June 1941 I guess you convert civilian factories to military like I always forget to do? Do you make very few ships to produce 40 armor divisions so fast? How many factories do you spend on fighters to prepare for Barbarossa? Do you not take Egypt before Barbarossa? Also it looks like from your comments the heavy artillery worked better than light spg if you got to Moscow sooner with heavy arty. Maybe the greater heavy arty firepower was more important than the armor and speed of light spg.

@steve19421945 It's highly dependant on micro, light spg is good cause its fast a bit more hardness, if u can overrun the opponent its gonna be better, if not, then probably heavy art (although doomed to be nerfed, already SS HQ getting removed next update). I have usually 40-35 mils on planes, thats what i put mils into first, then med bomber and then i put mils into tanks and so on. you wanna have 15 mils on heavy art from start of the game (if you wanna do the heavy art strat). There is also the fact you go Goering for 20% mil construction speed and you build mils from the strat of the game (not like vanilla where you build civs instead). Go harsh quoatas for all nations and the garrison use grenzwacht. Egypt is irrelevant in singleplayer, in multiplayer you're gonna send tanks there obviously but in singleplayer it doesnt matter, u can go and take it if u want but it doesnt change much. You will have resource problems like rubber, tungsten etc in 39, but if you bomb the maginot and get france before 1940 you will get all the tungsten from portugal, spain and rubber u wanna start building it late 38, before then mils then after u have enough rubber build fuel silos and buy oil from soviets (counter intuitive i know but you have to if you wanna have fuel at all)

I was building civilian factories till 1939 because I remembered a tutorial years ago but that must have been for Vanilla. Have not found tutorials for Total War but have not checked recently on You Tube. --------------------------------------------------------------------------------------------- I thought taking Egypt was good to help keep Italy from being invaded later but I have noticed the western allies do not invade France anymore in this mod at least before 1943. --- A tutorial said garrisons should use armored cars and hospitals to protect them from too many losses but that is for vanilla. Does this mean garrison fighting ability does matter to reduce garrison damage so upgrading them makes sense? Garrisoning Poland and France has been a head ache.

Do you train some of your troops? ---------------------------------------------------------------- Building 5 million oil storage capacity then buying oil is better than my strategy of building oil plants which takes too long so I do Barbarossa too late. ------------------------------------------------ I was experimenting with Germany licence building Japanese 1940 carriers but could not find how long does Japan get the factories they get in the deal in the wiki or any where else. I checked special project civilian factory usage and nothing appeared about factories going to Japan. Maybe this way I never have to research carriers to invade the USA. It has been a while since I have progressed that far at medium difficulty when Barbarossa was easier. ----- Thank you for your help.