I wear all self enchanted items to reduce magika use by 100% on two schools and magica regen. Then I go with resist and health enchants after that. I play with 0 armor rating too.
Which schools? Destruction and..? Impact Turret? Another nice thing about DiY is with a 0AR 100 health Pure Mage, you can add Health/Regen to your Robes/Jewelry, which is otherwise unavailible. Robes/Necklace/Ring of Health/Regen really helps with the squishyness, while you can Fortyfy School on a Circlet, Hood, or Hat.
I used this on a Majucka Pool Breton, who didn't need resistance, or Regeneration added. Also, a Conjurer with Alteration can o recover before they time out. Simulcast Ebonyflesh/Dremora Lord, then switch to Dragonhide while they're busy with Sir Stompy. "No Match At All!" Enough Health, and you don't need Armor, as much. (Can't summon reliably with Spell Absorption, though, so these techniques can't be combined effectively.) Goes double for Thralls, which you can all ready have out when you're attacked.
The best mix of enchantments really depends on the build. That's why DiY is probably best across the board, because premade robes have a much more limited selection. Don't forget the Shrouded/Jester/Cicero's Clothes for the stealthy types, too. The Archmage's are Just regeneration, with a splash of omnischool discount. An Enchanter, who mostly uses staffs has no need for Magicka/Regen, but Fortify Destruction lowers the discharge of staffs, and can activate Keening at 100%. (That's the only reason I ever made such a Glitch Suit, it's such a stompy Athame'.)