Inside path to stop slicing

Here's a way to make sure you are bringing the clubhead from the inside.

Put something like a plastic water bottle about 18 inches behind the ball standing up. On your backswing take it inside the bottle and on the downswing do the same. If you can't keep from hitting  the bottle than your clubhead is coming from the outside.

If you want to spend the money, The Inside Path, does the same thing. You can get it for less than $50 if you look around. Still too much money though but it does work.

Bottle works almost as well.

Another similar drill is to take about an 18" length of soft pine 2x4 and lay it so that the near edge of the board is about 2 to 3" from the opposite side of the ball from where you adress the ball.

In other words the opposite side of the ball from you. 

Make sure most of the length of the board lays behind the ball.  You don't want to come into the ball and hit the end of the board.  If you come from outside in you will hit the top of the board.  Start with half and three-quarter swings. 

The feedback is a little harsher than the bottle method but it will sure make you want to come from the inside.

Good luck!