If somebody has come close to a head on whilst orbiting in the circuit, then one or both of the parties involved were flying some pretty poor circuits.
As for speed, power settings, bank angle etc... just keep them the same as required for a standard circuit. As 2 Donks says, the whole point is just to create some separation from other circuit traffic, so at standard circuit speeds, the controller has at least some idea of where you will be relative to the other traffic following your orbit before requesting you to do so. Full power, max rate turns probably aren't the way forward.
If in your opinion, an adjustment is required to any of those settings, then make it, just the same as you would if you were failing to maintain adequate separation elsewhere in the circuit.