What are some tips you won't find in a guide for boosting DPS?

I've read all the rogue guides, but I still do low dps relative to the other rogue in my guild despite having similar gear, the same talents and the same enchants. Is there a good way to identify mistakes you're making and then practice them away?

So far I know you're supposed to do this on bosses: 1 combo point slice n dice, 5 combo point expose armor, then alternate slice n dice and expose armor. That I can do. My problem is on trash packs I can get 900+ with adrenaline rush and blade flurry and trinket, but otherwise I'm sitting around 500 while the other rogue sits around 700.

So I was wondering if I was falling victim to some sort of common new (to this expansion) player trap or some other kind of dps loss that was easily corrected yet not commonly found in guides.