Assuming the grip, aim, stance, posture and a proper club selection has taken place - by looking carefully at the lie, checking the wind, where the ball is going to land (pitch) and what you want the ball to do after it has landed - the next move is the first move.

But, hold on a second, why do we assume that all of the above is as it should be?

I have always believed that the first move is of the utmost importance as within two seconds the ball is on its way (well, most of the time!).  But there is little point in starting the swing in motion if the aim is incorrect, the club selection is poor and you do not know what you want the ball to do when it returns to the ground.