Do not move until the very end.
Eye-tracking technology is very sensitive to movement. Not moving from the original position is key to improving accuracy.
Use Eyes only.
Eye-tracking technology calculates the movement of the eyes and translates it into (x,y) coordinates. Moving your head does not help. It will reduce the accuracy.
Make sure your eyes are visible.
Because we are tracking your eyes, your face and eyes must be on the screen. If not, the resulting data will not be accurate.