There are a lot of ways to swing the club, but the most consistent players have the left wrist, left forearm and clubface on the same angle at the top of the backswing. The way to accomplish that is to keep your left wrist flat (above). If the wrist is cupped (bent inward) like @SteenSimon had it in one recent Twitter exchange or bowed (bent outward) like @KeithMorris23 in another, you'll have to re-route the club on the way down to compensate.
When the wrist cups or bows, the club will be either across the line (pointed right of the target) or laid off (pointed well left of the target) at the top of the swing. If the club is laid off, you'll tend to cut across the ball from out to in. If it's across the line, you'll tend to swing too much from in to out. Get the shaft on plane with the clubface square—and your left wrist flat—and you'll have the best chance to hit consistent shots without having to make any last-second recoveries.
When you have some extra time to practice, go out and play a two-ball scramble with yourself. Hit two balls on every shot, pick the better one, and play from there. It'll show you your potential. Ray Romano did this with me on Golf Channel for "The Haney Project," and he shot 73. It shows you the gap between your good shots and bad shots.
*Hank Haney is based at the Hank Haney Golf Ranch in Lewisville, Texas. To get fixed in Golf Digest, send Hank your swing on Twitter: @HankDHaney