filmtips:
The trick is to divide up the image with two horizontal lines and two vertical lines; unless your subject is to look straight into the lens and placed centre of frame youll find it more aesthetically pleasing to position your subject on one of the vertical lines.
This is particularly important where the subject lets say an interviewee or an actor is in conversation with somebody out of shot. Its important to position them in such a way as to have space between their eyes and the right (or left) of frame.