Regarding FDK in general go see main topic on fdk dps here on forums
https://forum.warmane.com/showthread.php?t=349828
My topic focuses on specific gear range and a bit different rotation.

So
How to min-max your dps before getting bis gear? Or more like how to get decent gear before 6k gs and still pump some big numbers?
Formula is simple:
x2 t9
x2 t10
max strength
mjolnir (yes, **** that scorpion bull****, mjolnir is way more reliable, and just better)

Since we have x2 t9 you MUST include Blood Strike into openings + MUST use Unbreakable Armor without wasting blood strike spot.
Opening with ERW looks like this.
9-10s before Army or DnD
2s before Horn
IT->PS->Burst Macro->Ob->BS->ERW->OB->OB->OB->cancelaura etc
or exchange obli and blood strike (still needs testing on what is better):
IT->PS->Burst Macro->BS->OB>ERW->OB->OB->OB->cancelaura etc

Regarding UA usage in fight. Basically you use UA macro AFTER x3 obli and then almost instantly cancel blood tap (around 9-10s on disease ticks), so this way you get UA + almost no delay on blood runes. And then just continue your normal rotation. Yes, you have to have good ping to do this.

Also, get a habit to watch trinkets and adjust your abilities usage. Like if Mjolnir procs f.e., Obliterate is your biggest prio, etc.


Regarding exact gear, here is example.
For 5.6 GS this is BIS gear:
https://www.wowhead.com/wotlk/gear-p...ANBgAKSeEgCdDw

With this gear you can EASILY do 11-12k dps on average in typical VOA25 fight. 13-14k+ if lucky enough.