How do I keep my armour from vanishing instantaneously

I’m new to the game, only bought it yesterday, and in the few games I’ve played (mostly 10v10) I’ve found that my K/D has been either 0.75 or worse every game. The main thing that I notice is that my tanks and tank killers seem to always instantly, and there’s nothing I can really do about it.

I’ve tried smoking my advance, using AT-infantry, using trees or any other cover, but it seems to be for nothing, as my armour just gets pummelled. Is there some sort of secret I’m missing? Any YouTube vids or forum posts or whatever that could help would be greatly appreciated.