A slice is one of a golfer's worst nightmares. It can appear to happen for no reason, but the reality is that there is a cause for your slice and you need to work to find it. A slice is the result of some breakdown in the fundamentals of your swing, and you need to re-establish your fundamentals.
Put the Ball in the Right Place
One of the reasons people slice the ball is because they fail to put it in the proper position in their stance. For woods and long irons, the ball should be even with your front heel. For middle irons, the ball should be in the middle of your stance. And for short irons and wedges, the ball should be in line with your back heel.
If the ball is too far forward in your stance, you will make contact later in your swing than you should, and your shot will go off to the left. If the ball is too far back in your stance, then you will make contact with the ball on your downswing, and this will cause you to push the ball to the right. Line the ball up properly in your stance, and it could help you eliminate that slice.
Keep a Proper Distance
If you get too close to the ball while in your stance, then you will wind up compensating by creating an outside-in swing. An outside-in swing results in a slice. To put yourself in the proper distance from the ball while in your stance, place your feet shoulder-distance apart. Flex your knees and then fully extend your arms with your club in your hands. Keep your back and arms straight, and lower your club to the ground. Flex your knees to compensate for any discomfort. Once you feel comfortable with your arms extended, you are in proper position. The ball should be where the club head is when you are in your stance.
A common habit among weekend golfers is to rock back and forth in their stance while they are addressing the ball. Some golfers claim this helps them establish tempo, while others are simply unaware they are doing it. Rocking in your stance will cause your weight to shift forward when you swing the club, and this causes an outside-in swing. The outside-in swing, as was noted earlier, results in a slice. Keep your feet planted to help reduce the possibility of a slice.