I always get told I have far too little Mana and Health for a Mage kitted out in blues and purples. Here are the main stats (with buffs):
HP = 5,613
MP = 7,866
Bonus Damage (Fire) = 824
Hit Rating = 131 (+10.38%)
Crit Chance (Fire) = 28.98%
Penetration = 30
Stamina = 240
Intellect = 387
Obviously my HP and MP suck, but my damage output is fine. Here is my armoury:
http://eu.wowarmory.com/character-sheet.xml?r=Auchindoun&n=Vortigun
Any advice you can offer whatsoever is useful, my Neck, Shoulder and Back pieces offer very little stamina... what do you guys think is the minimum required stats for Karazhan/Heroics.