If your talking big pulls like BL hard really all you can do is flash and cos. if it's 3 mobs I typically double flash, cos, then do my roh rotation but swap mobs as you go. 1st and 2nd attack same mob, tab target, roh different mob, tab, reappeat.

With the way targeting works you should tab in the same mob till you have gone through them all.

Also don't forget to mark a mob so your dps stay instead of following your target.