One of the most overused comments I hear golfers use is that they "looked up."
Telling someone they "looked up" during their swing is a wastebasket term, meaning the person saying it really doesn't know what caused their missed shot.
In order to really look up before you make contact with the ball, you would need to turn your head toward your target before you made contact with the ball.
If you set up to your shot with your head positioned slightly behind the ball, turn behind the ball and maintain good posture and balance both on your backswing and forward swing, your head will be behind the ball at impact.
However, if you let your trailing shoulder push your head toward the target on your downswing, someone is sure to say you "looked up."
Two professional golfers, Annika Sorenstam on the LPGA Tour and David Duval on the PGA Tour, appear to "look up" before they make contact with the ball.
In reality, their posture and balance is maintained perfectly through impact.
Maintaining posture and balance during your swing will cure "looking up."