The proper use of smoke grenades - Men of War Assault Squad

I have a question about how to use smoke grenades. Most infantry seem to have them, and they are the obvious solution for attacking an strong enemy position (i.e. trench, field gun, tank).

I seem to be having issues on higher difficulty skirmish against the AI with the position of my smoke screens. I'm not sure if they are meant to be on top of the position you are attacking, or between your current position and where the enemy is located. It seems like either method leads to my infantry getting torn apart.

What is the most effective method to deploy a smoke screen, and how are units affected by them?