Ok here are some common or detailed tips that come in my mind quickly.

1. Infantry is everything, spread them out good. A good starting is smg or paratroopers (since they have anti tank right away). If you have smg you could rush towards a first support vehicle. Or if unsure you take a bazooka. But remember:
smg + bazooka = 16 points, paratroopers = 15 points + are elite (aim better, are more deadly, can run faster).

2. For Germans any tank that is below a hetzer can be counted as crap if that tank is not used in the first 5 minutes for quick control.
3. T70 in early games can be devastating, most earlygame units cant crack the hull from the front, only the turret could be damaged. Tho make sure you have the front towards the battle.
4. Su-76 is a cheap infantry killer, number him and bombard your enemy, also making a crater "path" to the enemy could be usefull for your own infantry.
5. An IS-2 can be taken out by a jagdpanzer at 105 meters (hull aim),
6. an IS-2 can take out the jagdpanzer at 90 meters.
7. molotov on engines = garanteed tank destroyed.
8. F5 for suppressive fire, meaning if you see a group, f5 and aim in that direction, they empty the whole clip at once.
9. Its better to have an ISU-152 then a SU-100 if you face a panther. for the same points you can also use that vehicle as artillery and it has a heavy machinegun on top.
10. Americans are very powerfull early game, m5, m19 and a scott combination are deadly. (anti tank, anti inf, small artillery vehicle).
11. Russian scouts are the best of scouts since they have 2 molotov cocktails.
12. If you attack a position best is to have 1. SMG, 2 mortar and 1 heavy machinegun. Spread them out, create a smoke screen and head in (this is for open battles), the heavy machinegun placement is very tough and quite small when someone is firing at it.
13. Placing a heavy machinegun in a crater will give the emplacement more survivorbility.
14. Mortar in trechens + sanbags = invurnable for artillery.
15. Panther V and Jagdpanzer IV have the same gun penetration.
16. The T34/85, KV-85, Is-1, su-85 have the same gun penetration, only their armor and speed are different.