More ever-valid tips:
Put at least one engineer in every infantry squad asap.
Rally points are the most OP strategic tool in the game. They win matches. Winning makes the grind shorter. BUILD. RALLY. POINTS.
Any tank, even endgame ones, will go BOOM as soon as you throw a TNT pack under them or in their tracks, or onto their roof.
AA guns are actually better at mowing down infantry than MGs.
AI in this game is 90% of times dumb as dirt and blind, 10% sniping people in the head at 100m through 4 bushes and a window. No middle ground.
Laying prone reduces the lethality radius of nearby explosions.
(Personal opinion) water flasks and binoculars are totally useless, don’t waste orders on them.