As a "beginner" (can't pass T4, haven't done any of the 2.1 content besides the HM dungeons and PS), I use the BB combo twice on single targets, then I try to keep Storm's path and storm's eye 100% of the time.

In a general way, I keep Storm's path 100% of the time, and Storm's eye whenever I can. Butcher's block is here to held you get a lead if DPs are coming close (shouldn't happen often. Pop some BB combo to keep yourself ahead).

for AoE pulls, 3* overpower is a nearly-guaranteed way to keep the hate for long enough to kill every monster around you if the dps are doing their job. In case of need, use HS+SS on one monster, then BB on an other, it should buy enough time to help the dps to focus.

Defiance should be on 100% of the time if you're MT. If you're the OT, you can let it down if you don't have to take back the hate repeatedly (T2 for example), and spam the storm's combos.

Berserk is a bit more complicated sometimes. I use it whenever it is possible when I OT, as better damages are always good, but when I MT I only use it on single target with unchained, to get a huge lead on hate so that I can perma-debuff the target when pacification turns off.