From: NE Pa, USA
I build 40 engineers on turn 1 and 2 trains (two 20 engineer units), with the latter coming in turn 2 if my capital city is a port and I build ships on turn 1. If I build fighters then my resource buildup is delayed but otherwise that is the critical part of the early game. Need like 200 in raw and as much as possible in oil so that is the primary goal early on. Unless I get attacked and have to defend myself, I just keep building up my resources, with more engineers coming typically.
Once war starts it is armored cars and artillery, and the AI cannot stand up to that, except you have to watch out for anti-tank weapons. If the game runs long enough, it is time to replace the armored cars with medium tanks (level 3) and they are unstoppable against the AI.
With this approach I typically run into situations where I am running out of oil every turn. Not much I can do about this, with all my oil up to level 3, but it just delays the inevitable.
If I get a situation where my cities are on a different continent and an AI is already there, or have very poor resources, or I get attacked by like 3 AI at the same time, that is when I typically lose. A matter of the 'luck of the draw', or lack thereof.