I'll usually use Circle of Scorn right before flash, as the DoT helps maintain hate on all affected mobs. It's useful when your party insists on spamming AoEs like flaming arrow and shadow flare.

For lower levels, it's more important that the dps is focusing on the same target as the tank, since your hate tools are more limited. Also, while Provoke is good for getting quick hate back on a de-aggroed mob, be aware that it only lasts for a few seconds, and you have to do some damage to that mob to maintain hate on it.