Nothing really major to add, but alot of T-34's left the factory unpainted, especially during the german invasion. They basically rolled right off the asembly line into battle. This would also apply to the tracks.
Like the previous posts, you can't go wrong as long as you keep your colors in the range of brown's, blacks, rust, and steel. In no particular order
You can take a look at Adam Wilder's awesome Russian Armor on sites like www.missing-lynx.com in the gallery section. I personally feel he is probably the best Russian Armor modeller around.