You're not hit capped. 15%
Mastery is king
Supremacy + Imp
I've been playing Destro since wrath and even though it has changed alot since then, the basics are the same
curse elements -> Immolate -> Conflag x 2 (I have it glyphed) 6 incinerates -> usually gives me two embers -> Two chaos Bolts that fly immediately after.
Also, on fights with adds include Rain of Fire into the mix, I know its not as good after the nerf but It can still help quite alot. On Nuroshen it's amazing!
I know a lot of people frown upon using a conflag buff to burn a chaos bolt but I do it quite frequently and it doesn't really cause much of a problem.
Sac is simply better atm than Sup on 90% of the fights