Level as frost, or frost/arcane: something like 10/0/42 or some such to pick up clearcasting.

I leveled in my max +spell damage gear, you could level in stam gear, or a mix, it would just take longer to kill things.

Get tailoring! Spellstrike is awesome for PvE, as is the set that goes with your spec, ie Frozen Shadoweave for frost and Spellfire for fire.

At the end, 10/48/3 is the full fire raiding spec which people claim, through massive testing and crazy math skills, does the most damage until you get 2/5 set bonus for tier 5, then full arcane is the best.

As full fire, you want spell hit, crit, spell damage, aim for around 850-900 fire damage then try to max crit, hit is most important.

For frost, most people claim crit sucks, but I always liked it, you want spell damage and hit.

Just a little bit to read through here. I can go more in depth if you want.