On a golf course, the only place you're guaranteed a flat lie is on the tee box. Some courses, such as Ballyliffin in Ireland, won't offer any other flat lies, which is what makes them fantastically fun to play. But even on pancake layouts you'll draw at least a few uneven lies, and on most courses they are commonplace.
The key to hitting accurate shots from these lies is building a strong stance that allows you to keep your spine angle as close to normal as possible. That enables you to turn properly through the ball and finish the swing. It's crucial to find some way to make a complete, balanced finish, with your chest facing the target. Depending on the severity of the slope, a full follow-through isn't always possible, but that should certainly be the goal. A complete finish signifies that you drove the clubhead through the ball solidly and under control.
On specialty shots like these, most Tour pros will grip down a half-inch or an inch as a way to enhance feel and control and to remind themselves that swinging hard isn't the point—hitting the ball squarely is. Basically, there are four types of uneven lies: uphill, downhill, with the ball above your feet, and with the ball below your feet. For all but the latter, when you are actually farther from the ball than normal, you'll benefit from choking down on the grip. The ball won't go as far, of course, but that's only one of many compensations you have to factor in.
Most of the shots you'll encounter on the course will be combinations—a downhill lie with the ball above your feet, for example—and it's impractical to try to cover all the permutations here. But what follows are descriptions of the four basic shots. These are only guidelines; the important thing is to get the feel of each shot beforehand. Your body really needs to come alive. Always take a few practice swings from a location near your ball to sense what happens to your balance, rhythm and follow-through.
The only way to improve at hitting from uneven lies is to put yourself in these situations. Many ranges have no slopes to practice on, except for on the sides of bunkers (which are perfectly suitable to use, by the way). So if you can, take a few extra practice shots during casual rounds. The next time you find a nice hump in the fairway, throw down four balls and hit one from each side. If you use a five-iron from the upslope, you might need only a seven from the downslope even though it's just five yards closer to the hole. Once you get the feel of hitting these shots and can bring that feel into your body, you'll discover they can be a lot of fun.
Ball Above Your Feet
When the ball is above your feet on a slope, it's closer to your body than normal, so it's especially important to choke down. These shots tend to go left (for right-handed players), because a flatter swing causes more right-to-left spin on the ball and you tend not to turn your torso as aggressively as usual, meaning the arms take over. When the ball's at knee height or higher, the arms are apt to whip around the corner and send the ball scalding off farther left. To avoid making the swing flatter than it should be, stand a bit more erect, and compensate for the slope by aiming to the right of the target. You can only know how much by experience.
The surest way to set up correctly is to pick an intermediate target a few feet in front of the ball, in line with where you want to aim—say, the green's right edge. Set the clubface square to that line, take your stance and then swing. Once airborne, the ball should come back to the left. Many amateurs, even after aligning themselves properly, don't trust their setup and swing back toward the pin. The result is often a low pull.
Another common mistake is lining up square to the pin and trying to do something during the swing to keep the ball from hooking. Some might try to move the heel of the club faster than the toe to hold off the release—essentially the same technique top players use from flat lies to manufacture a fade—and that can work. But even the pros have a hard time pulling it off consistently, and for most everyday players it's wishful thinking.