First mage, need help with rotatoin

I started a Fire/Frost mage a day or so ago, he's level 26 now, and so far I think mages are quite neat. I just want a rough idea of what I'm getting into, I just notice that even heirloom gear I am not putting out the damage I would desire.

So far, (main spec fire) I am keeping my Polyblast ticks up and spec'd into Ignite and Impact, so I'm always proking Fire Blast as much as I can, as well as taking every proc of Arcane Missles.

I know that as I level it will get better and easier, but this is my first mana using ranged class I've played so help from experienced mages would be appreciated :>