I must be missing something. The AI out-produces me even on the normal difficulty.
What faction are you playing, and what is your economy looking like?
Ive not played very far into any campaign yet, just fucking around with different factions. It feels like Im too slow though, even when I produce units as fast as possible with my first city.
Don't let any unit die; retreat them if neccecary. They get a 33% healing bonus inside outposts. Building them over again wastes resources.
I would say... keep your very few units, say three infantry, fighting together early in the game. Have each one cover the other, so that they overwhealm anything that comes into range with overlapping fire. Explore in one direction, taking as many outposts as possible. Upon suspicion that one faction is nearby, halt. Muster your resources then push your lines forward to outside their city, overwatch killing anything that comes out. When you have enough blast weaponry or overwhealming numbers, you can wipe them off the map.
You are a German; Guderian's legacy is in your blood sir. Follow your Deutsche insticts; nothing piecemeal, when you come, you come in force.