The most common slicing mistake is a weak grip. But many golfers with good grips slice because they rotate the clubface open and don't square it coming down. To fix this, lead with the heel of the club in the takeaway, with the back of your left hand flat and your knuckles pointing down. This will keep the face from opening and help you square it up.
Shanking comes from overactive hips and shoulders on the downswing, which push the arms away from the body and create an out-to-in swing path. This move exposes the hosel of the club at impact, leading to a shank. To ingrain the correct in-to-out path, pull your back foot away from the target line 18 inches at address. From that closed stance, hit some full-motion, half-speed iron shots, keeping your back heel on the ground for the entire swing. This will help you swing your arms down in front of your body and make sure your hips and shoulders don't interfere with the club path or release.
How To Vary Loft
To control pitching trajectory, set the angle of the shaft at address. For a normal pitch, lean the shaft slightly forward; for a low shot, lean it more; for a high shot, lean it slightly away from the target. For each, square the face, angle the shaft, then stand to the handle so the grip points at your belt. That establishes the correct ball position.
Drill: Cheek Check
Proper hip action back and through leads to solid ball-striking and powerful shots. Try this exercise: Take your stance with your rear end against a short wall or fence. Make some practice swings, and monitor your contact with the wall. If you turn your hips properly, your right cheek should still be touching the wall at the top of the swing, but your left cheek should not. As you start down, your hips should slide toward the target, with your right cheek staying on the wall. The correct hip sequence is lateral then rotational.
I see a lot of players with an open clubface at the top of the backswing, the toe of the club hanging toward the ground. This causes them to come over the top on the way down, with the left wrist cupping upward at impact. The result is usually poor contact and a weak slice. A great way to fix this is to imagine you're pitching a baseball. When you throw a ball, you naturally cock your right wrist backward. If you can do that on the backswing, your left wrist will flatten, and you'll square the clubface at the top.
To hit crisp pitch shots, the sole of your wedge must emphatically bump the ground, not just brush the grass. When this happens, the clubface strikes the ball at the same time, and the ball pops in the air. Here's a drill you can try at home: Practice pitching a Ping-Pong ball on your living-room carpet. This will help you develop a feel for simultaneous impact with the ball and the ground. Make your normal pitch swing, and listen for the thump of the carpet with the click of the Ping-Pong ball. Transfer that feel to your pitching on the course.
Read Bunker Lies
In the sand, your first priority is to assess the lie: Fluffy sand and good lies call for a skimming action. Firm sand or bad lies require you to dig to get under the ball. A sand wedge has more bounce (this makes the club skim rather than dig) than a lob wedge, and opening the clubface or leaning the shaft away from the target at address adds bounce. Squaring the clubface or leaning the shaft forward decreases bounce. Experiment with these variables to handle different bunker lies.
The conventional advice of accelerating the putter through impact, especially on speedy greens, is risky. From my experience teaching on the super-fast surfaces at Oakmont, most three-putts come from poor speed, not poor direction. A pendulum motion is the way to putt fast greens. Your putter should move in a calm, gliding motion, even with a very slight slowdown through impact if your ball position is forward, as many golfers prefer. So to master those fast greens, stop over-accelerating.
Play Long Irons Up
When hitting a longer iron, the bottom of the swing should be in line with your left shoulder. Play the ball just behind this position, because contact should come on the downward part of the swing arc but very close to the bottom. As you swing, stay centered just behind the ball, and keep the club's grip in front of the clubhead through the strike. This ensures that the bottom of your swing stays in front of the ball for solid ball-striking.
A proper shoulder turn is a key to maximizing power and accuracy. Hold a club across your chest, crossing your arms in an "X," with the grip end pointing at the target. Set up over a ball as if you were hitting a middle iron and swing back, turning your shoulders perpendicular to your spine angle. If the grip end points at or inside of the ball when you get to the top, your turn was too steep. If the grip points well outside the ball, you're too flat. The grip should point about a foot outside the ball.