http://skyrimcalculator.com/#64537
This is my current build.
I run with robes, and finished Winterhold College yesterday. It was surprisingly easy actually.
I mostly up my mana at every single level up. My health is around 180 I think, with around 380ish mana.
Once you start doing a few of the quests, you get things such as the Saarthal Fragment (+30mana) and a mage circlet (+40mana) as well as good robes (-12% destro cost, +50% mana regen)
Also, my char is altmer, so I start with +50mana, and their racial is absolutely beast. For a full minute it can spam dual cast fireballs without ever going OOM. Well, it does, but the racial brings me back to full mana in a few seconds.
Having alteration armour has been really good. Currently using stoneflesh-I need to go see Tolfdir about Ironflesh. The armour I get is more than enough to mitigate melee damage, and I always have fast healing as a back up.
My destro is around 60, same with alteration. Granted, I boosted destro at the start of the game by continually attacking Hadvar with flames, lol. Got to around 40destro before I reached Riverwood for the first time
Once you get the Arch Mage robes, everything is really nice. -15% on everything,+50mana and +100% regen makes everything die fast due to abundance of mana. The necklace you get (+50magicka) from Savos is also really good. My firebolts cost like 10 mana, fireballs 37. Can cast 10+ before needing to recharge.
Once you get started and have a lot of the perks, it becomes much easier. I haven't bothered at all with alchemy or smithing.
I have levelled enchanting to around 50, but not taken any perks with it yet. I did enchant my gloves +20mana though, and that's without perks. Enchanting+mage style looks like it's going to have such great synergy.