"The key to a good bouncer is most definitely the height. The aim is to get it over shoulder height to the batsman. So he cannot play a controlled shot, and untimely hits the ball in the air to a fielder.
The bouncer, should be bowled with maximum effort to enable you to get the height and speed you need to surprise the batsman. You need to deliver the bouncer with the intention to hurt the batsman. Pick a spot on the wicket about half way down and slam the ball on that spot as hard as you can.
The bouncer should be used to surprise the batsman. So don’t over use it. But if you feel the batsman is getting comfortable with good line and length then use the bouncer to put doubt in the batsman’s mind."