Most swing errors happen when you push your backswing beyond its natural limits—that is, when you try to make a turn that's too big for your physique. You not only lose your posture and balance but your timing, too. Here's a simple range drill to help you find the perfect backswing length for your level of flexibility.
Take your normal setup, and without turning your hips, raise your right arm as though you were holding a tray or a pizza box. Hold it as far behind your right ear as your shoulder will allow. Now join your left hand (and the club) to your right hand. This is your natural turn! No need to go any further. From there, you'll have the right blend of power and control off the tee, leading to more birdies and pars.
It's tempting to overswing, but your lust for extra yards can cause mis-hits. To learn where your backswing should end, take your address and hold an imaginary tray behind your right ear. There's your end point. From that spot, you'll have the right blend of power and accuracy.