Gonna start going solo unless I know I'm going to go fight a dragon / big fight. My companions just make it easier for me to get detected.
I have 100 sneak, every sneak perk. Shadow Stone power. Throw voice shout. My guy is near impossible to spot. Muffled boots, muffle spell. Last step is getting my illusion skill a bit higher.
Still get killed sometimes by basic enemies like cave bears one on one.