Hey, my best guess would be put together a set that has as much multistrike as you can, obviously. After that, I think haste carries a lot of weight at lower ilvls, especially after the frostbolt buff.
Copeland's Clarity is extremely overbudget regarding the on-use effect, so that's definitely one of the BiS trinkets. I've used the Alch trinket as well for my gold and realm best runs, if you have access to that. The CC on-use stacked with the Alch proc is really nice.
So, to reiterate, I go, Multi>Haste>Crit>Vers=Mastery.
Different things might work for different people, but this has worked well for me. Also, BiS trinkets will probably change once new raids come out, but this is what I've been doing for now.