Current single target DPS is as States
Thunder 2 > Fire3 > fire > Fire > Fire (use firestarter procs whenever they come up) > Fire > Blizzard 3 > Thunder 2 (if you didnt have thundercloud proc) (blizzard (if you didnt get your two mp ticks) Fire 3 > Rpeat process base of situation.

Its a simple rotation that all BLM will use to bringg out their damage. Make sure to level Archer to atleast 34 for Qualling strikes and also Raging strikes.

BLM in itself until 2.3 a simple roation DPS class hopefully the changed in 2 weeks will shed some light on a better rotation for DPS