that's lame though, i want to be able to play like a mage with mage clothing. i think i'll be able to pull it off as long as i get the right perks and figure out good spells to use(and enough magic to use them)
Staying in a robe will be tougher. But good on ya for fightin the power. Well since its in combat that you have to worry about running out of magicka its destruction magic you need to bulk up on spell cost reduction for. 4 items with +25% reduction to destruction spell costs will make destruction spells free to cast so you can use your magicka for your summoned creatures, protection and healing spells and just chain cast incinerate all over the place without having to worry about its cost. If your going to stay in a robe you will need the dual enchanting perk as soon as reasonable to load up on the +health, +magicka, etc you will need beyond the +destructo enchants already mentioned.
My mage was a pure destruction mage. He cast very few spells outside of the destruction tree. He very rarely used illusion or restoration spells. Conjured every so often but way over 99% of his casts were destruction (with most of those being incinerate - I LOVE that spell). He was very powerful but he wore the best heavy armor, fully upgraded, dual enchanted. I have no idea how that would have turned out if he had stayed in robes. Good luck.
And dont listen to those saying the Arch Mage Robes are best. The Master Robes of Destruction are better stats and you will probably move on to enchanting your own robes once you reach 100 in enchanting anyways.