If you're using the 'standard' build of 54/17/0, you should priority queue rather than use a rotation.
1) Make sure rend is up (let it fall off before you re-apply)
4) Mortal Strike
5) Slam (this is your filler when the others are on cooldown)
Use bladestorm whenever it's reasonable to do so, though I tend to use it when AOE is needed (great on Kologarn when you're DPS the arm and on Hodir when there are a few ice blocks close together).
If you have decent gear, you should have the rage to use every GCD to do something. I'm far from practised at arms specced (I went fury at ~62 and was prot from 70-80) but I still managed to get 3rd on dps on Kologarn. It's been majorly buffed in 3.1.