There are two theories when it comes to chipping: 1) You chip with a variety of different clubs and get the ball rolling on the ground as quickly as possible; and 2) you use one club to chip and you learn how to make that club work for you. Mickelson is in the latter camp. He chips almost exclusively with his 60-degree lob wedge, because he’s figured out how to make that club do what he wants. He understands spin and how the ball is going to react coming off the clubface, and he can dictate the trajectory and amount of carry and roll he wants, which is crucial in the short game.
Most amateurs chip with only one club – usually, a sand wedge – but either their technique is bad or they haven’t spent enough time practicing with it to get a sense of what it can do. If you’re only going to use one club, make sure you practice with it enough so that you know how it's going to perform on a consistent basis.
From a technique standpoint, keep the handle of the club forward of the clubhead at address and through impact. If you watch Mickelson, you’ll see that his hands are well forward through the extension of impact and beyond. He’s got the shaft leaning towards the hole and maintains that angle through impact. Amateurs have a hard time keeping this angle, especially with a lob or sand wedge, because they’re inclined to help the ball up in the air. Phil delofts the club significantly through the shot. If you want to learn how Lefty does it, head out to the chipping area and see how low you can hit the ball. This will force you to keep your hands ahead and the shaft leaning forward, so you’ll hit the ball with more spin and control.