Practice this tempo and timing drill: Hold the clubhead end of the shaft in your grip and practice swinging back and forth, keeping the grip part of the shaft about 12 inches above the ground. The club will feel very light--what you are trying to make is the loud "swoosh" noise made by the club as it swings through the air, traveling into the hitting zone where the ball would normally be. This sound will only be produced if your timing is correct. After doing this for a few swings, grip the club normally, but make the same smooth, rhythmical swings. You will feel the weight of the clubhead at the end of the shaft--try to recreate the swooshing sound at the same point in your swing as you did when you held the clubhead.
Tension, anxiety and nervousness will automatically force you to swing your club too quickly and unsteadily, preventing you from swinging with tempo and balance. Clear your mind of any doubt or negative thoughts. Focus on swinging smooth and steady. Keep your arms relaxed and tension-free. If you find your timing, rhythm and tempo are off, try swinging your club at half speed. Committing to 50 percent in both the backswing and the downswing will help you regain your tempo.