Accuracy and steady rhythm are rare commodities. They're elusive for one reason -- the animal urge to pound the ball. Whether it's trying to bust one 300 yards off the tee or stretch a 9-iron from 150 yards, overpowering the ball not only kills control, but makes it difficult to establish a steady rhythm -- a must for consistent golf.
The key is to change your attitude on the course and tame your killer instinct. Instead of viewing the game as "let's see how far I can hit it," think of it as connect-the-dots. Hit it in the fairway, hit it on the green, one or two putts. To promote this change, play a few rounds dropping down two clubs on every full shot. For example, if you ordinarily hit a 7-iron from 150 yards, hit a 5-iron. Off the tee, try to hit the ball 20 yards shorter.
The only change in technique this requires is swinging easier. Don't shorten your turn: Make a full swing, just make it slower and softer. Not only will you benefit in accuracy and rhythm, but the new swing will give your entire game an injection of feel. You'll have a better idea of what you can and cannot make the ball do.
Drill: The 100-Yard Shot
If you have trouble throttling back try the 100-yard drill. Start with your wedge. Try to hit it 100 yards. After a few shots, take a 9-iron and hit it 100 yards. Proceed throught set, trying to hit each club 100 yards with a full swing. It becomes difficult in the mid- and long-irons, and far more difficult with fairway metals/hybrids/drivers, but going to extremes gives you an idea of how it feels to tone down your swing.