A slice is caused either by an open clubface at impact or an out-to-in swing path. A block to the right is typically caused by a shallow swing path or a clubface open to your target. To correct these issues, check the following elements of your setup and swing:
Your grip controls your clubface. Make sure the “V” you’ve formed with your thumbs and forefingers point toward your right shoulder (if you’re left-handed, your left shoulder). Keep the grip presure light–a tight grip will keep the face of the club open.
Take a practice swing and stop your follow through at the halfway point. Check to be sure that the toe of the club is pointing up and that your right hand is released over the left hand (reverse for lefties).
General Swing Problems
Make sure the ball is not too far back or forward and that your alignment is square.
Always check your divots after a shot. If your divot is too shallow and angles from inside to outside, then you’re coming at the ball to far from the inside. If you’re making deep divots that angle to the inside, your swing is too steep.