@Conni_Hu Because you asked for a non-specific answer:
Overview: You need to make a beeline for Moscow ASAP, but also make sure to scoop up Leningrad along the way, as it is the main point the Western Allies will attempt to land in to reinforce the Soviets. Making any effort to attack southern Russia or North Africa (beyond just using the units you began the game with in those areas) is ill-advised, as capturing Moscow will effectively end the game due to the USSR no longer being able to collect income or field an army.
Round 1: Attack East Poland and Baltic States with everything that can reach. More should go to Baltic States.
Round 2: Attack Belorussia and Leningrad with everything that can reach. Most of your troops should go to Belorussia.
Round 3: Attack Moscow with everything that can reach.
What you do in other areas of the map is outside of the scope of your question, but you should be taking steps to slow down the USA/UK Navies.
If this answer is too in-depth for you, I apologize. Please refer to just the “overview” for the shortest possible explanation.