To control the direction of a heli during a pirouette, pick an imaginary rference line passing through its center. Every time the helicopter’s nose come around and crosses that line, give a control input in the direction you want it to go.
For example, if you’ve done a pirouette in a hover in front of yourself and you want to fly straight away, imagine the line going straight out from the heli. Then wait for the nose to come around. As it aligns with the imaginary line, start to give it a small amount of forward cyclic. Then go back to neutral (don’t hold the control input very long). The short forward input will nudge the helicopter forward. When you want to go in another direction, just pick another imaginary line, and give a small foward input when the nose comes to the line again.