10/48/3 SpecFollow

I've been following the famous 10/48/3 spec for fire and loving it, I'm currently lvl53 and have put everything so far into fire. Now that I'm getting close to filling out the 48 part is there any preferred order to fill in the rest of my tree, ( arcane or frost first?)

http://www.wowarmory.com/character-sheet.xml?r=Burning+Blade&n=Dustoff

I would do frost as it will allow you less resists