When using the rest it is important to get the head of the rest, properly positioned.
Keep your elbow parallel to the bed of the table, and the same height of your cue.
When possible the head of the rest should be no further than 15 inches away from the cue ball.
Keep your cue on line of the shot after hitting the cue ball, Like in Photo 1.
Don't finish to the right or left after hitting the cue ball, Like Photo 2.
Keep your cue action smooth and follow through the cue ball every time.
Avoid raising the butt too high, as a downward action creates side on the cue ball.
Commons Faults
Elbow facing the bed of the table instead of being parallel
Not on line after hitting the cue ball
Over Stretching
Bad Cue Delivery