It sorta helps to use Berserk on cooldown if possible. The pacification debuff serves as a pseudo-TP regen.

Unless of course you've got a great healer who Esuna's you, or a BRD that knows to put Warden's Paeon up.

Having said that, a good general rule is to Overpower a group = to the number of mobs in that group (unless you're doing a mass pull with lots of AoE, then just spam it with Bloodbath up to your hearts content). So ideally, a group of 4 will = four OP's. You can toss in a Flash in place of an OP, or while you're getting the mobs set up so that they'll all get hit by OP. Just be mindful of Flash and it's weird mechanic of leaving a "light bomb" that detonates a half second after you actually use the skill.

As noted above, Steel Cyclone is your friend. It's a 200 potency attack that I think has at least a 2x emnity modifier on it. Opening with an SC > Infuriate > SC will cement aggro on you through damn near anything.

Give it some more practice and you'll find the rhythm that works for you. On your average pull of 2-4 guys, I'll use the Overpower rule above, then cycle into my normal combo, tabbing between targets to check aggro and laying SS or BB down as appropriate to keep hate. Once I've got 5 Wrath I'll SC and that's almost always enough threat for the rest of the fight without having to tab swap during my main combo.