You will find from experience on the range that you cannot keep your head in one spot if you stiffen your muscles in any way.
So keep loose yet try and keep your head still and behind the ball when you swing at the ball.
It will cause you to finish the stroke smoothly, naturally and easily, and thus prevent slicing, because you will not have to depend on your hands to restore your balance as you will not lose it.
Regardless of how much you perfect your style, you cannot develop any method which will not require you to keep the head still so that you can see your ball clearly.
It is worthy of notice that there's no good player out there who does not observe this fundamental principle.
Out of Bounds: Golf is always testing your skill against your opponent's luck.