If USA commits towards the Atlantic, recognize that germany’s main goal is to survive. Try to maximize infantry purchases each round with rare exception. Trading territories back and forth very efficiently is okay, but avoid large trades such as trading germany air for Allied navy.
Check every round whether allies can safely stack Northeast Europe or France. It’s absolutely critical to calculate this each round and have enough units in reach to prevent this. You don’t actually have to occupy France and in many cases occupying France is inefficient.
Try to position to stack Karelia and check every round if you’re able to. Getting UK and US bottled up in Sweden is a very common way that axis wins.
Japan buying mostly infantry and tanks will be able to start trading with Russia starting round 3 around kazakh. Japan with starting air can trade very efficiently, and this weakens Russia. Japan should focus on expanding income. Taking india is not necessary and in many cases suboptimal for Japan to try.