I hardly ever see Russia except in forged referers from Ukraine ;) The rare "real" Russians, unlike the Ukrainians, seem to be legit.
I've seen a few techniques but I don't think anything is fullproof as they can always use a proxy.
Truism: It is impossible to design a foolproof system because fools are so damned ingenious. But that doesn't mean you shouldn't start with the basics, like IP ranges. Why bother to use a proxy when there are completely unprotected sites sitting out there?
Besides, the proxies themselves are-- or should be-- on the Deny From list.