Ben Hogan fought a hook for most of his career. One of the ways he combated this problem was to work on his grip.  More specifically, he constantly checked his right hand grip position.  If the right hand is too far underneath the handle where the "V" (the line between the thumb and index finger) point to the right shoulder - a strong grip - the ball will tend to hook. 

 Coin Drill

Place a dime between the thumb and index finger of the right hand.  Hit several balls keeping the dime in tact. If the dime slips, it is likely that the right hand grip has slipped into too strong of a position.  This is one of the best hitting ball drills for developing a consistent neutral grip.