Make a point to acknowledge your misses. Practice is being honest with yourself.
Most people tend to practice by swinging as fast as they can. That's like trying to hit a 70 mph pitch when you can really only handle 40.
Before you can hit a ball far, you must first learn how to control the face. Learn how to use the face of the driver to your advantage.
Face control is necassary before speed. Feel how to create spin on the ball.