One thing that I see all the time out on the lesson tee is the tendency for people to be very quick with the start of the downswing, especially when going for "extra" distance. This type of motion can lead to the club getting "off track", also known as "casting", as well as the upper body lurching forward on the downswing, resulting in a loss of distance and direction.
Swing thought: Making a reasonable shoulder turn, keep your back to the target as long as you can on your downswing. As the lower body starts the downswing, feel your arms fall at a speed close to a gravity drop. You should begin to feel your downswing path coming much more from the inside with a shallower angle of approach into the ball.
Drills: Tee to ball. Place a tee into the grip end of your club. Begin the downswing by pointing the tee at the ball. This will help establish a proper downswing path.
Gravity drop: Extend your arms out at shoulder height. Let them fall by force of gravity down to your sides. This is the same feel that you should have as you start your downswing.