Re: to look at opponent's eyes or not?
I've always been trained to maintain initial focus on the third eye, that is that space slightly above and in between both eyes.
It's pretty simple to test. Just stare at someone at some point on their body, be it a leg or an arm or their eyes or whatever. Then ask them to quickly attack you with random attacks. Nothing serious, just in an attempt to get in. Tell them to include both kicks and punches. Feel how long it takes to respond. Then do the same thing while staring into their third eye. See if it's any different. It always seemed to be to me.