Great marketers know that people don't buy products; they buy a story.

Since Apple is one of the greatest marketing brands of all time, it's worth watching Tuesday's virtual event for tips on effective storytelling.

Before launching a string of new products and services that included two new Apple Watches and an iPad Air, chief executive Tim Cook set up the presentation by spotlighting Apple customers. 

"I love reading the many messages I get every day from Apple Watch users telling me how the watch has changed--and, in some cases, saved--their lives," Cook said.

Cook shared the story of a young girl named Ray from Texas. As photos of Ray filled the screen, Cook narrated the story:

"She had been experiencing pain in her stomach but didn't think it was too serious. When Apple Watch alerted her to an elevated heart rate, she realized it really was. She went to the ER where it was determined she was in septic shock. Ray got immediate intervention, but she could have died without that warning from her Apple Watch."

Cook then shared the story of Enrique from Spain. Enrique is blind and uses his Apple Watch "for everything from speaking the time to reminding him when his appointments are to calling taxis and to helping him keep fit."

Cook's stories of Enrique and Ray were just the beginning.

"Now I'd like you to meet a few more people and hear their stories," Cook said as he introduced three short videos: An athlete who uses the watch to monitor her diabetes, a man who started exercising to reduce his high blood pressure, and a 26-year-old man whose watch alerted him about a serious heart problem.

Here are three keys to customer stories the Apple way.

1. Keep stories short.

None of Cook's customer stories lasted longer than 35 seconds. 

Cook told Ray's story in 27 seconds and Enrique's in 18 seconds. The three videos were 30 to 35 seconds in length. 

There are two big problems that I often see in business and sales presentations. First, they're heavy on data and light on stories, the emotional component that connects an audience to the speaker. Second, when stories are told, they are far too long.

Long stories lose their impact. There's power in conciseness. 

2. Share at least two customer stories.

High-tech companies in Silicon Valley--some of which are seeing record sales even during the pandemic--are increasingly training their sales professionals to share at least two customer stories in every pitch. 

I'm seen data from some of their tracking software that records and evaluates the effectiveness of customer stories. Sales professionals who don't use any stories close fewer sales than those who are good storytellers. But telling too many stories leaves little room for facts, data, and demos. 

Two or three customer stories seems to be the sweet spot. 

3. Have a beginning, middle, and end.

All stories have a beginning, middle and an end. The formula applies to a two-hour movie or a 30-second sales pitch. 

For example, the video of Kate the athlete only runs 35 seconds but tells an entire story with a beginning, a middle with a conflict, and an ending with a solution. 

Beginning: "My name is Kate. It has always been my dream to become an Olympian, but that can be hard with type 1 diabetes.

Middle (problem): "It was so many shots and finger pricks every single day."

End (solution): "I went from having to take my blood sugar manually every 20 minutes to--now all I have to do is just glance down at my wrist, which reads the insulin pack attached to my side. I feel like I don't have type 1 when I'm competing now."

Tim Cook has earned a reputation as one of the most admired CEOs on the global stage, an extraordinary accomplishment given that he took over for the legendary Steve Jobs. If storytelling is a key component of Cook's product launches, it might be worth adopting in your next presentation.