Every unit has a special ability (e.g., Smoke Screen for tanks, Sprint for infantry). Use these constantly; they are on short cooldowns and often save your units.
If the game crashes randomly, try switching from DirectX 10 to DirectX 9 in the Graphics Options menu. World.in.Conflict.Complete.Edition.v1.0.1.1.par...
In team play, you must pick a specialty. Each has a specific responsibility: Every unit has a special ability (e