In my opinion the Russian strength is in the mobility of their armor. This translates as faster speed and less chance of bog in scattered woods. Looking for nice hull down postions to face off with German armor simply doesnt work (with T34s) as you will lose most frontal engagements. Playing the Russians is much like playing the Americans in France. It's vital to close with the enemy armor, within 300m if possible, by using terrain to probe deep and flank. This is the Russian strength. In 1943, you can get 3 T34/76s for each Panther or Tiger the GE player buys. In 1944, you can get ~2 T34/85s per. I've spent most of my time in CMBB honing this skill, as I can't find any better one to win.
The Russians also have a very cheap (~30 pts) 45mmL66 AT weapon that can take out GE cats with side shots (at 800m+), and these have become my main frontal AT defense. Hidden until the targeted vehicle turns to engage the T34 approaching his flank.
Seems difficult to win with the Soviets at first, but by playing as them regularly, I believe you become a better overall player.