As the Russian player, continue to stack infantry on Russia and Novgorod. Also, a nice compliment of mobile (ie: tanks and mechanized infantry with movement 2) stationed at Bryansk with your air corp at Novgorod makes a nice counter-attack force that can hit nearly every territory along the Eastern front.
For Germany, by turn 4, that player may have wanted to consider buying more mechanized infantry earlier, and more consistently, as it allows fresh troops to catch up with the asualt eastward, preserving your high value tanks up to the gates of Moscow. It also allows you to capitalize on gaps in soviet defenses to blitz through (tanks + mech inf) in order to unbalance and pose new threats to the Soviets.
Enjoy!