Little pitch shots, like the one below, drive golfers nuts. First off, they use too much loft. The more loft you have, the bigger swing you need. And more swing means more things can go wrong. So unless you have no green to work with, keep your lob wedge in the bag.
Second issue: Most golfers don't trust the loft they have, so they try to add more at impact. They flick their wrists, dip down, rock onto the back foot ... I think you see where I'm going here.
Let's give you a simple plan for hitting the basic pitch. Take a narrow stance, with the ball about middle, and favor your front foot (1). Lean the shaft a touch toward the target, and keep your grip pressure light.
Swing straight back, and let your wrists hinge with the momentum (2). Don't add hinge, and don't let the club sweep inside—both lead to fat shots.
Swing down and through the grass. A good trigger to start the downswing is to softly shift your knees forward. The clubhead should stay low after impact (3).
Keep turning so you face the target. Your arms should be soft and your weight on your front foot (4). Now go make the putt.
A good test of whether you made the right amount of swing for the shot is how you finish. If your follow-through is very short, you probably swung back too far and had to dump some power. If your finish is much longer than your backswing, you didn't take it back far enough so you had to accelerate wildly through impact. You want your follow-through to be smooth and unforced, and your finish slightly longer than your backswing.