Trying to keep one's head still when playing golf literally is both a snare and a delusion. It is a snare because it makes it hard to relax. It may add a quite unnecessary rigidity to the swing. And it is a delusion because most good golfers do in fact allow their heads to move. Not only do they rotate their heads slightly but on full shots they allow their heads to move back and down several inches.
What has to be kept still until the ball has gone is an imaginary point at the base of the neck, which only adds to the difficulty for many people, I find.
It may be better to forget about it and, instead, train oneself to ''watch the strike.'' Do this in slow motion for practice. Start, maybe, with a putter. See the clubface hit the ball.
On a full swing see the blur of the clubhead as it swings through. Then look up.
But never look up until after you have ''seen the blur.''
Add to this the feeling that until that moment your chin stays the same distance from the ground and you will have it made.