This is what I do:

I pull with Shield Lob, wait for the enemies to gather, then Flash (remember - Flash's range is quite small despite the animation). I do the Fast Blade > Savage Blade combo on the enemy I pulled. After that, it's useful to rotate Fast Blade and Savage Blade among your other targets. Flash alone is less hate than your combo, but you should still be using it as soon as the Blind effect from it wears off, as this makes it last the longest it possibly can, gives you hate, and enemies missing means that your healer has to do less healing and therefore gets less hate.

Also, make sure your party members are fighting the enemy you are currently fighting. If you rotate it shouldn't be an issue but it is very important that parties focus down enemies so they need to be assisting you instead of doing their own thing.

I would say maybe get some practice running Sastasha, Tam-tara, or Copperbell as other players are still learning the ropes in those dungeons and there is a shortage of tanks. Good luck!