My suggestion to you would be to plan out a build with what you think would work and post it in the Blaster forums so people can have a look at it. That way, they can make suggestions on power picks that you've selected/haven't selected and possible slotting strategies. You can use an offline hero planner such as Mids Hero Designer or an online planner such as SuckerPunch's .
I have started an Ice/Fire blaster, and can't find a guide anywhere. I really like the toon, but was hoping to avoid any pitfalls when picking powers. Any suggestions?