When confronting a villain or ruffian (or sparring with a fellow practioner) where do you look? In my experience, Japanese martial arts tend to encourage students to look their opponents dead in the eyes. I was once told that the reason for this is that an untrained attacker will often look at a target before executing the corresponding attack. Indeed, it did work to some degree. When playing tag with some of the lower ranking students, I was often able to anticipate the next move based on where I recognized their attention being. When working with higher ranking students, however, that advantage no longer existed as they were sufficiently experienced to locate targets without needing to glance away from my face. I find it very difficult, ultimately, to pick up on subtle eye movements, especially in the heat of the moment, for the practice of looking at my opponents eyes to confer a meaningful advantage.
At other times in my practice, I was told to look at the pectoral area, because that area will have to move before launching any sort of attack, and so it provided the greatest amount of telegraphing from my opponent.
Another teacher would instruct me to watch my opponent's lead elbow, which would have to move to throw any hand technique. (As for techniques using the legs and feet, I would need to rely on my peripheral vision.) In this particular system, once a practioner makes physical contact with the lead arm, he/she would then watch the elbow of the arm he/she was not in contact with. And every time that contact changed, so too would the focus of the eyes. I actually found this method made my life much easier, once it was sufficiently trained.
I am wondering though, what are your prefered methods regarding the use of your eyes?