Some tips probably stated above:
Use and abuse the gun, Russian heavies from the KV-1S to the T-10 (old IS-8) rely upon their gun and mobility to out trade opponents, and preferably outplay by flanking, baiting a shot, etc.
The armor is good, for a medium. These heavies are pseudo heavies also named heaviums due to having the best of both worlds. They retain some mobility from mediums while gaining a punchier gun and better armor. However this armor should not be relied on too heavily unless you have placed yourself in an advantageous position as it can pull some bounces off but i