Elemental theme: Ice/Fire or Fire/Ice? How best to build?

[TungstenShark]

I have an elemental-themed character (not very original, I know) who I might try to play as a Blaster. I never had a Blaster back on Live as they really do not suit my play-style, but I figured I'd take the opportunity Homecoming has provided and try all of the ATs. Are there big differences between Ice/Fire and Fire/Ice? My other question is survivability...how best to build one to get at least some semblance of passable defense/resists?

[Marshal_General]

I prefer fire/ice. Ice gets its sustain aura at level 10 with some nice effects along with the other nice powers /ice gets