I only play dead-is-dead. The experience is significantly richer when you have to pay attention every moment rather lollying around knowing that you'lll just reload if something goes wrong.
As a play style: I do not abuse the system or power-level; I roleplay the character with their imagined background.
120 hours and ten characters later, here are my thoughts on how to survive the game all the way to the end, I hope:
(TL;DR: heavy armor; block; focus on few skills)
*** You must limit the damage you receive: i.e. either crowd control or stealth or tanking.
Crowd control would imply *conjuration* or *illusion* (*alteration*/paralysis is available much later; you may not make it that far). I prefer to be self-reliant and crowd control is not reliable for me: if a far away enemy (Draugr Deathlord with a bow) can one-shot you, a far away enemy WILL eventually one-shot you because you won't notice it in time. Stealth isn't my style. I leave the commentary to the experts. However, I find that there will be cases when stealth will fail and you will have to tank a Draugr Death Overlord with a Greataxe hacking at you. *gulp*
This leaves (for my play style) tanking: I find *block* a necessity for tanking. Most of my deaths are when I fail to kill things fast enough that they are still hammering at me while I'm out of stamina, mana, and potions - and fail to run away. *Block* + *Heavy Armor* reduces the rate you receive damage significantly, *block* additionally lets you avoid power hits and reduces elemental damage via perks.
*** Controlling level scaling by focused character development.
In short, if you become a level 20 master of speech, pickpocket, and alchemy you will be dead!
Choosing Heavy Armor & Block naturally suggests *One Handed* as the primary offence and one secondary attack skill: archery or destruction (or conjuration, but not my style). Alternatively you can have *one handed* as a secondary to destruction/archery.
I prefer not to level sneak: it would make sense for a dedicated character with an archer/assassin build, but it dilutes the sword-n-board build I discuss here.
*** Survival
Either you are killing them fast enough before they kill you or you must increase your longevity. *Alchemy* or *Restoration* are natural candidates. Assuming you are not using crowd control or stealth, you will take damage.
In my opinion, *restoration* is useful ONLY for a heavy armor + block warrior. Otherwise, you are taking damage too fast (die in 1-3 hits) for healing to be relevant. I use restoration dual cast to step back and full heal (+stamina, using respite perk) and go back to the fray: that essentially let's you have a second chance to continue fighting the same mob. If I cannot take them down that way I must run away as I am over my head.
Alchemy is a personal choice of all-or-nothing. Your mileage will depend on how much you invest (and it increases your level, making mobs tougher).
*** In summary, here is my "paladin" build for attempting a dead-is-dead run:
Block, Heavy Armor, One Handed, Restoration, Destruction.
Past lvl 20, I may add Enchanting and/or Smithing, but I do not abuse the crafting system. (If I craft I only use found materials: the dinky smith in town shouldn't be able to stock dwemer ore and whatnot.)
(Minor details: 1. I will keep Lydia for role-play reasons and made her essential - I don't think it is possible to keep her alive otherwise. 2. I will play at Adept difficulty: died in Expert too many times, Adept is hard enough for dead-is-dead unless you are powergaming. 3. I use one mod only that scales Destruction damage ~1% per skill. I find this a reasonable compromise that should have been in the vanilla already.)