Playing on normal difficulty.
Level 33 now.
About 70 conjuration and smithing.
Been easily making do with the flame and frost atronach spells, but now have Dremora Lord too.
I picked up Erandur as a follower early.
Big help.
He's wearing exquisite ebony armor now.
Gave him a superior glass battle axe.
But he hardly uses it.
I give him every staff I find.
He's a maniac with them.
He'll have a familiar going, a reanimated corpse, and be throwing fireballs and electricity left and right.
He's died only a couple times, once from Chaurus poisoning, once when I accidentally whacked him.
I reloaded of course.

I only carry Wuuthrad. Powerful, and traps souls. If I need a bow, I borrow Erandur's.
And I buy/steal every common/lesser/petty soul gem I come across.
This keeps all of Erandur's staffs charged up, and increases the enchantment skill rapidly.
But I haven't enchanted anything yet. Might not even get to that.

Here's the thing.
I've watched Youtube vids of boss battles and they go on forever,
Slashing, weaving, dodging, restoring, bonging potions.
Mine are over pretty quickly, and I often never even use my battle axe.
Erandur and the frost atronach do all the work.
Not complaining, just observing.
Now with the Dremora Lord spell, I expect it will get even easier.
That's okay for me. I'm not too good at the dodging/slashing method.
And I enjoy staying hidden like a little coward and watching my minions do the work.

So if you like doing it my way, here's some advice.
Get Erandur, and concentrate on conjuration.
Carry a spell trap weapon and collect soul gems to keep Erandur charged up.
Boost your magic and health about equally when you level, and wear magic enhancers.
I'm at 340 for both health and magic, wearing arch-mage robes and other enhancers.
Stamina is 130. I haven't noticed any issue with low stamina - and I do some hacking.
Use smithing to boost your level when you get bored.
Perk the casting distance and magicka cost for conjuring, and the weapon damage perks.
Don't know yet what I'll do with the 10 unused perks I have.

Anyway, just some observations. There's a million ways to go about it.
One other thing. If the enemies shout, check that Erandur hasn't been disarmed of a staff.
I was recharging his stuff and noticed he lost the Magnus staff.
Should have kept that stored away, but I don't think I need it now.