I don't know what you're doing wrong, but I can tell you what seems to work for me.
I usually only cloak when moving from cover to cover, or if I'm being shot at and can get behind cover. If I cannot get behind before death, armor up and return fire. Don't stealth while being shot at unless you have something to block the bullets... It'll just drain your energy bar and ensure death.
I've gotten into the habit of just hitting armor anytime I'm about to fire at someone. In the event there's return fire or there's another enemy firing from the side/back, I'm covered.
I can say that probably 75% of my deaths come from behind. Outside of wearing headphones (which I do occasionally, but I think since I haven't worn them in a quite a long time, my ears aren't trained to drown out the gunfire so it's almost impossible for me to hear footsteps) I can't think of a way to avoid this other than luck.
This said, I'm not the best of players either. I'm like level 25 with 1.32 K/D ratio. I think the rest just comes with time.