The best way to achieve control over continuous orbit is to pick a point actually on the model and imagine that you are grabbing it and spinning it. It is much easier to communicate the desired speed and direction in this way. Note the similarity between the action of continuous orbit and the free rotation or constrained orbit icon. The grabbing and turning are the same, but continuous orbit keeps moving when you release the pick button, whereas free rotation stops. Also notice that however complex your dragging motion is, continuous orbit registers only one vector, the speed and direction of your last motion before releasing the pick button.