Use AMS effectively, and spam FS until it drops off. Maximizing the amount of frost strikes you put out while capping runes the least amount possible is the key to DW dps. You need to know exactly how much RP howling blast gives you and use HB and FS accordingly, trying not to cap runes and RP at the same time, but prioritizing FS if both cap or KM is up. Basically you're looking to dip into fire or anything that gives you RP whenever you have AMS off cd and you have used up most of your resources.
Also, dropping OB from the priority is an increase and simplifies the priority a bit. DnD/PS(if pillar up) with the U rune when you're resource starved and need RP (or you're applying BP to the target / dropping DnD below an AE pack.)
Edit: For encounter specific stuff, lets see..
Norushen: always mouseover howling blast where there are the most adds. HB hits the boss from the adds but not the other way around for the little adds.
Juggernaut: goblin glider 1 of the knockbacks, with heroic galakras trinket you're able to avoid all the knockbacks this way. 1st and 3rd you have pillar up and you goblin glider the 2nd one. The spikes and red circles on the ground also give RP, soak whatever whenever you have AMS. Managed 380k on this today, damn logs not working.. 01:12:30 for how the glider thing works
Malkorok: use AMS every cd since there's static environmental damage during the normal phase. 418k nologs /cry
Spoils: mouseover howling blast the target that has the most mobs in their proximity, and this goes for all AE as frost, unless you really need to prioritize single target dps since the target you hit with HB takes full damage from it.
Thok: I just AMS here every cd since there's nothing to lose, almost everything's physical, but when you get a full RP bar from something random it always helps. I think spirit link actually gives RP or something.. And yea, I think you're less likely to be targeted with the fixate thingy if you're not one of the farthest people from the boss. You can pretty safely stay at or near melee range for the first 3-4 fixates and nuke the boss.