You slice severely because you cut across the ball on your tee shot. Your might have lifted your forward heel up off of the ground during your backswing or allowed your back shoulder to lean forward during your forward swing, causing you to swing over the top.
You want the ball to fly further off of a tee shot.
You are uncertain how you should angle your feet or find that you are losing power or swaying due to angling your feet incorrectly.
You need to learn a quick and easy way to check your posture or you want to try to correct a flaw in your swing with no known cause.
You hit a 3-iron off of the tee a little thin and off towards the right of a tight fairway.
Too much loft due to too much of a lateral movement of your lower body during the downswing and turning your back hand under the forward hand.
Each time you are faced with first tee jitters, water hazards, or other obstacles, you lose confidence and fail to make a smooth or successful drive.
You might be attempting to aim right of the target but find yourself heeling the ball or are shanking the ball with flight towards the right.
You lose distance on your drives due to a severe slice. This might be from an exaggerated open stance or an out-to-in downswing with the clubface open. Another possibility that is often over looked is the driver that you are using. It could have too stiff of a shaft, be too long, or it may not have enough loft.
You need to learn how to or improve your pre-shot routine.