Forget about the Arcane tree while leveling, its benefits are for raiding/pvp, and is pretty much useless for questing. If you're leveling as Frost, just focus on the Frost tree only. Frostbolt leveling goes for Shatter as priority, Blizzard grinding leveling goes for Permafrost/Imp. Blizzard as priority. As for Impact: 1 point in Impact is worthless and apparently it is still bugged and does not work after using Ice Block.
I'll give you my mage's tree as an example, he's Level 48 atm.
Frostbite+Shatter helps out tremendously for leveling. I have enough Spell Damage to where my Frostbolts will crit for about 1k, and Winter's Chill allows me to essentially drop Intellect for Spell Damage pieces without gimping myself out of spell crit. This is making leveling a breeze, and lets me easily solo quest elites that usually require 3 or more.