One key to a smooth stroke is a relaxed transition from your back stroke to your forward stroke. Let the momentum of your back stroke come to a natural pause before letting the pendulum motion carry your cue forward.
Do not lunge forward in your execution, instead concentrate on your forearm being the only moving part of your body as it swings effortlessly back and forth. Your warm up strokes are not just for aiming, the also prepare you to deliver that smooth stroke.
HOT TIP: Get Smooth