Iam a beginner myself but I think that might help some people. Feel free to criticise or expand this list.

1. Dont play 1vs1 as beginner. 1vs1 will overwhelm you plain and simple. Your Units will die while you are elsewhere and you wont even know what happend. Start playing bigger maches because that reduces your part of the frontline and helps you to keep track.

2. (Cheap) Infantry is your Meatshield. I know it sounds brutal, but it is the Infantrys job to die to protect your other units. But dont send them out alone, they need something (if possible Tanks) behind them to kill the enemy.
If your tanks lead the charge, dont complain that a single enemy AT Inf kills 10 times the points of its own worth.

3. Elite Infantry (especially the ones with AT) is for defense.

4. Flamethrower or grenade Inf like the German pioniers are urban fighters.

5. Dont move Pak in the line of fire of other units. Yes Pak counters Tanks, but if your men have to move it, turn it and aim, while the enemy tank fires at them with 3 Mg`s and it`s canon they will die.

6. Scout cars and other light vehicles are for herassment, not your Tanks.

7. AA mostly scares planes and only sometimes kill them. Fighters reliably kill planes. Most AA can be used efficently in Ground to Ground combat.

8. Arty mostly scares other units only sonetines kill them. Kill the scared units with your other forces. This rule is especially true for tanks.

9. Recon is important, you cant react or kill what you cant see. Best position for your recon is a place that gives you a wide view range but is not directly on the enemys attack path. Turn off the weapons of your recon or set their engagement orders to only return fire.

10. Try to create efficent platoons. A Platoon in this sense is a group of units that are balancing each other out and are close enough together to help each other. But dont have them to close together to avoid being a juice arty or bomber target. The buff range of leader unit is good indicator how far you should spreed your units.

These are my major points that I learned from playing myself and watching others play.

I hope it helps some people.