Well the way to use EE imo is to use a totem of the opposite element and simply spam whatever. If you are set on using 2 elements, I'd do Infernal Blow on one side, Lightning Strike on the other. Mostly LS to clear trash mobs, maybe you get Molten Shell too so you can LS the mobs once with like chain or fork(cheaper) then Molten Shell pop them all for one shot. Then what you do is when you're fighting tough mobs or whatever, you have a spell totem setup with 2 minor trash spells of each element, I'd do firestorm and arc for example. Also can replace firstorm for a pure flame totem. Then you drop your opposite element totem, it procs EE and you smash the mob in the face with LS or IB. You pick whichever depending on the base monster resist(if cold whatever doesn't matter).
Totems are great source of cheap quasi permanent EE procs for an opposite element of what you use. You could alternate but alternating is much better if you're using spells than attacks, because you have more choices and everything is aoe(kinda) so you can do it properly even for trash. As a melee it's a much more complicated affair. Oh also what really fucks you up as a melee is you can't use a weapon with any +elemental dmg on it other than the element you're not planning to EE off. If you have +lightning dmg on your gloves or weapon then your IB increases resists to lightning and fire, so your next lightning hit is mitigated, ruining the point of the skill. Works fine with totems but not if you plan on alternating hits.