Use your putting grip, and play the ball just inside your left heel. Set the club on its toe so the shaft is vertical, like a putter's.
Paul Runyan, my friend and colleague for more than 30 years, was a master of the short game. In the 36-hole final round of the 1938 PGA Championship, he beat Sam Snead convincingly. Sam was outdriving Paul by 50 yards, but Little Poison won, 8 and 7.
Paul's mind was analytical, but he was also creative. One of the concepts he pioneered was to chip like you putt.
Paul didn't mean to just use a putting grip, which helps minimize wristiness for more reliable contact, especially under pressure. He also showed me how to set the club on its toe so the shaft is more vertical, similar to a putter's shaft. Setting the club with the heel off the ground:
Helps replicate your putting stance, so the ball is more directly under your eyes, and your motion is simpler.
Encourages the clubhead to slide through the grass, guarding against mis-hits.
Promotes contacting the ball toward the toe of the club, which gives the shot a softer feel and allows you to make a more aggressive swing.
Take your normal putting grip (I use a reverse-overlap). This helps keep the back of the left hand stable. Play the ball just inside your left heel. If the ball is sitting down,tilt your upper body a bit to your left. This encouragesa slight angle of descent through impact.
Keeping your body still and with a pendulum motion, swing the clubhead up with your arms going back, then let it swing down into the ball.