http://wowtal.com/#k=Zwl97eN4.aei.mage.RY7nCM try out this build - i use it myself and it gives me quite nice dps.
About rotation: personally, I open with Scorch, Living Bomb and Flame Orb then I spam Fireball until i proc Pyroblast. Refresh Critical Mass and LB when needed and cast Flame Orb when it's avaible - with Fire Power it will give nice dmg and will explode at the end of it's duration. I use Conbustion Helper to know when I should use Combustion - when LB, Pyro and Ignite are on, use it, that's the best dmg. Ofc with Molten Armor on.
I usually use Mana Gem when I run out of 50% of my mana when at 30~40% I just switch to Mage Armor. Master Of Elements and Arcane Concentration safes ton of mana. This rotation is for bosses, ofc. When fighting trash, use Mage Armor and cast your instant Flamestrike or Blast Wave if you have at least 2 mobs - Flamestrike will be cast aswell. Evocation should be your emergency when you really need mana or you're dying and healer can't heal you. Also, remember to use Mage Ward or Mana Shield or Ice Block when you pop Cauterize.
I know I wrote basic basics but I hope that at least part of it can be useful for you.