Here are the strategies I think need to be employed in Free For All Games, which recently have been sprouting up on the boards.
Russia: Russia has to worry about Germany primarily. Japan is a secondary concern. Russia would be wise to engage Japan in some arrangement that limits that liability. I recommend offering them the far eastern states and unopposed invasions of Chinas in exchange for security from further invasion. This should prevent you from losing resources trading with them (3 IPC in lost income is less then 9-12 IPC in lost units taking and defending land against him.) It also allows him to focus his force on America.
Germany: Germany has to worry about Russia and England. Russia is by far the bear you don’t want to tackle right off the bat. As such, why not make an arrangement with Russia giving them W. Russia and Ukraine in exchange for a DMZ of Karelia, W. Russia, Belorussia, Ukraine and Balkans where neither side stacks more then one infantry as a picket? Now you can work on building a fleet to A) take England and B) Stop America from ever being a threat to you.
England: You have issues. Sorry, but it’s true. Your only hope is to ally yourself with the two axis powers. 1) To stop Germany from attacking you and 2) so you and Japan can disassemble America before they can create hegemony.
Japan: Japan can be a real thorn in everyone’s side. If you have a VC game, you can win almost every time. If you have a more regular game, you may be wise to make alliances with England and Russia so you can focus on one major target.
America: You’re the target. You and Germany are the two easiest to hit because your lands are in danger and your forces are going to be strained protecting it all. Write off China/Sinkiang, maybe even Hawaii. Focus on fleet in the Pacific giving Germany the impression you are not a threat. This should prevent them from allying themselves with Russia.
England is NOT a threat! You may want to trade England Brazil for East and West Canada. A) The canadas are hard for him to defend. B) Brazil is hard for you to defend anyway. This way you don’t lose units taking and holding both.
Focus on the Pacific. You are the only one stopping Japan from a VC win. You might be wise to form a non-aggression agreement with England (after you trade land of course.) This should allow England and Russia to work over Germany while you hold Japan in check.
Just my opinions.