As America this is my favorite strategy right now. I say right now because all strats are beatable and therefore change.
Turn 1, buy 1 Bomber and 2 transports 1Armor and save 3IPC
Fly Fighters and Bomber to Britain (Note if Britain bought an AC then they go there, if not one fighter stops for a turn in eastern Canada.) My fighters will continue on to Karalia on turn 2.
Use the Transport in the Pacific to block while the Battleship heads for Panama and the Atlantic.
Load 2 Infantry on transport in the Atlantic and drop them in Spain. Pay the 3IPC
From this point it never goes exactly the same. I try to buy I bomber a turn and fly them to Britain. I buy Infantry for the west coast a little at a time. I build 2 transports when ever my fleet is in port so my fleet is consolidated and safe.
In Spain I have a few options. If Germany takes it I land in Gibralter. If Germany takes Gibralter I take Algeria. If Germany leaves it alone I begin to stock pile there and draw the German forces away from Eastern Europe and Africa. If I need to I can transfer troops to Africa or Finland.
I also begin strat bombing germany on turn 2. If I make an attack into Europe I can use my bombers and fighters to support that.
If the German sub hits my Transport in the Atlantic I sink it and delay my plans by one turn, however with the delay I will be stronger when I hit Spain.
Most important is to keep it as flexable as possible.