When I watch amateurs chip and pitch the ball, the first mistake I see them make is picking a club without even looking at the shot they have to hit. They just pull their favorite club around the green, usually a sand wedge or lob wedge. When you do that, you've already dictated what you have to do. And it probably means having to cook up a shot using the wrong club.
Tour players do just the opposite: They assess the shot, then pick the club. Look at the lie, how much carry you need, how fast the ball will roll, and where you want to land it. Then select the club that gets you to that landing spot with the right amount of run on the ball. A lob wedge will settle quickly; an 8-iron will scoot. Having more options might sound complicated, but it actually simplifies things. By changing clubs, you can hit a variety of shots with the same basic swing.
Here's a good rule around the green: The more the ball is sitting down in the grass, the more loft you need and the steeper you have to swing into impact. But when the ball is sitting up, a steep swing can make you slide right under it. In that case, you need more of a sweeping motion to catch it solid. So remember, when the ball is down, hit down; ball up, sweep it.
Butch Harmon is a Golf Digest Teaching Professional.