Don't be afraid to use CD's religously. Hand of sacrifice on every other pull, wings, the haste/crit move I forget the name and aura mastry. I judge and arcane torrent on cd more or less and do fine. Let others said, the first few heroics will be rough. Carry mage food and just drink each pull if need be. Try to que with a decent tank or buffs that may help, MOTW, Intellect etc. Try to avoid divine light spam. My ilvl is around 350 in all pve gear and 100k+ mana buffed and I can't even get away with too many divine lights. Maybe once the divine Plea buff goes live it'll be worth using on CD, as for now, i rarely use it. Gem properly and get 2 good raiding professions that provide bonus intellect. Reforge mastry/crit to spirit/haste depending on whats available.
Good luck