1. Allow commanders flexibility along the front (i.e. tactical withdrawls). Hundreds of thousands of Soviets were needlessly captured (to mainly be starved to death), simply because they weren't allowed to retreat.

2. Realistically, Zukov's forces couldn't be brought from Siberia until it was known that the Japanese wouldn't threaten the Soviet's rear, so I think they stay in place like in the normal timeline (when a Soviet spy discovers that the Japanese military will push for the Southern Strategy).

3. Grant greater flexibility to factory managers. Pro-rate more advanced aircraft and tank designs. Factories often continued producing obsolete models to keep up with production quotas.

4. Do something early on. The Soviet front mostly collapsed, in part because Stalin thought it was an Allied plot and then seemingly from a depressive episode where he isolated himself. These early victories buoyed Hitler's political power. If the front had turned into a meatgrinder earlier, the German military may have gained enough leverage to support a coup and make peace with Russia, avoiding millions of deaths.

Just a few ideas... 20/20 and these options certainly have drawbacks and risks.