The average slicer doesn't turn the upper body enough on the backswing, then turns too much on the downswing, producing an outside-in swing path.  To fix this slice-producing move, your arms need to swing from the inside and lead your body.

Set up so the ball is directly in line with the logo (on the left breast of your shirt).  On the backswing, turn far enough so the logo points well behind the ball.  Then keep the logo pointing behind the ball while the arms swing down; they will pull the body and club through impact.