New here to these forums, but not gonna hijack...
I had started a new character and I built a full daedric set, armor, shield... Everything. But I still getting destroyed like nothing. On Adept no less. So I looked, and my health was... Minimal. You'll need a couple things to be very durable (And I know this by experience. My rogue is VERY durable. I'm almost impossible to kill on Master.):
1) You'll need to hit the armor cap of 567 (I think it is. Something VERY close to that if i'm wrong.). This grants 80% physical damage reduction.
2) Magic resistance. This is crucial to making dragons and mages do significantly less damage to you. Capped physical and magic resistance make you a forimdible tank. Well, when coupled with #3...
3) Make sure you've dumped enough points into Health. You could have high damage and magic resist, but if you're only at 200 health, you're going to get eaten alive. Health is the REAL armor in this game.
Make sure to cap those off, and you'll be fine.