1) Hold your finishing position until your ball clears the pin deck. Even if you think that you did something wrong during your approach and/or your release, hold your position rather than giving up on it. You'll find that your ball will do wonderful things as it makes its way down the lane. People always talk about follow-through and this is a way to ensure your arm accomplishes that.
2) Trailing leg behind you and toe on the ground (Off to the left for right-handers, off to the right for left-handers). Your leg should be as far off to the left or right as is comfortable and that you are not curled up at the line. This gets your hip out of the way and allows for maximum leverage at the point of release. By keeping your trail leg on the ground, you keep your body in balance and not teeter-tottering at your finish position. (A two-point finishing position as opposed to a standing on one leg.)
3) Knee bent at the finish. As well as helping with the leverage, this will accommodate a smoother release of the ball onto the lane. How much should the knee bend? As much as is comfortable for you to achieve that smooth delivery onto the lane.
4) The pendulum armswing. Most of us are taught to hold the ball with both hands in the starting position. Once the non-ball hand drops away and you start your downward swing, don't exert any force on your armswing. The weight of the ball should be all that's necessary to carry your ball through the backswing and forward to your release. In a "perfect" armswing, your arm should feel weightless through the entire arc of the arm swing.
When done properly, these four pointers will help you post your shot and increase your probabilities for throwing a strike.
Not only will your scores improve, but, you'll begin noticing why other bowlers are not carrying their pins as much as you are.