Many of the beginning players I work with seem to hold back as they swing down to and through the ball, finishing with 30 percent of their weight on their right foot (for right-handed golfers). It's almost as though they are trying to guide the ball toward the target, rather than making an aggressive, full swing. I suspect that they believe that the more conservatively they swing through the ball, the less penal a mistake will be. Not only are they losing power by hanging back on their right side, they're also making the game more difficult. It's so much more difficult to consistently repeat a less-than-full swing--that's what makes a delicate pitch shot so much harder than a full 7-iron shot.
To hit consistently solid shots, you can't hold back--you've got to "let it happen." Your right side needs to fire, your clubhead needs to release and you need to extend down the target line to a full finish. To make sure you're letting it happen, see that you achieve a full finish position every time:your belt buckle, your chest and your eyes should be facing the target and your weight should be completely off your right foot.
At the finish, you should be able to lift your right foot off the ground and maintain perfect balance. Think of a hockey player following through after a slapshot--his right skate is usually completely off the ice!