When I HAVE to play as Russia, I use a strategy I haven’t seen very often. I buy a plane, and all infantry. Then, I draw extra protection from the allies (like planes and men - which does slow the allies advancements elsewhere) to make up for the 4 less men (since I bought the plane). I try to buy a plane as often as possible. In longer games, by turn 3 or 4, Russia has a good sized air fleet and infantry.
Thus Russia can attack around itself (the planes, if left in russia, can easily move from russia to join infantry assaults on the west against germany or east against japan). And because you pay for the planes instead of tanks, you never have to leave anything but infantry when trading territory with japan or russia, giving you the absolute best bang for your buck.
The strategy takes a small drain on allied forces (britain shunting planes and some men to defend russia early on), but can ultimately result in Russia being more than able to defend itself, the trade-off is that the allies have to slow their efforts in africa for a while (though America can still do that while Britain builds up Russia).
Against experienced players it would probably result in your immediate death - but against moderate players I have a good time with it. So I thought I’d share - sorry if it’s been shared a hundred times already.