It's not how much you shoot, but how well you shoot. I try to make EVERY shot perfect. The most difficult part of perfect shot placement is how you work the trigger. Learn to use your finger tip, and not your 1st knuckle. Your finger tip gives you much better trigger control. Some people tend to over-grasp their revolver. This is not going to yield good shot placement. You should hold your revolver firm, but not so firm that it affects your trigger pull.
Another common problem is, most shooters have an "anticipation of ignition". In other words, most people jerk their pistol in anticipation of a shot being fired. You'll never have a tight group if you "anticipate" your shot and jerk the revolver. This is very difficult to overcome. The easiest way to overcome this, is to have someone else load your revolver while leaving one chamber empty. When you attempt to fire on the empty chamber, your "anticiaption" will be obvious as you will shake or lift the revolver. Teach yourself not to anticipate your shots, but just let the hammer strike happen, regardless if it fires or NOT.
With good technique and practice, you will easily have every shot touching one another on your target.