She explains: "Zi wei is the purple star, the King of Stars. It's known as the North Star in the West.
"Dou shu simply means calculation."
Ba zi are the eight characters derived from one's hour, day, month and year of birth.
She says: "There is no fixed or best method. It just depends on what you have learnt."
When she begins the reading, Madam Cheong says she also observes the customer's body language and little actions that betray their emotions or thoughts.
She says: "The way they respond will also give me a heads up on whether they believe me."
Madam Cheong picked up the trade from her grandfather.
He was a fortune-teller in Penang, Malaysia, but is now retired and "biding time before he returns to ashes", she says.
Madam Cheong recalls: "I have always been fascinated by how people used to approach him for anything and every- thing.
"Some neighbours even asked him to locate missing chickens or dogs!"
She used to help her grandfather set up his "office" - a foldable table and six chairs.
Her role included "taking appointments and giving out queue numbers". Much like a secretary, she jokes.
Madam Cheong confesses that she chalked up misses among the hits when she first starting reading fortunes.
She says: "I can't claim to be 100 per cent accurate. There were a few occasions when my predictions were off.
"Sometimes, it can also happen when customers give me the wrong details. A mistake in the minute of your birth time can make a big difference."
Honing one's skills is very important. She says: "You need to keep reading up and studying the charts. Every two years, I take a three-month sabbatical and go off somewhere to medi- tate."
It's also "extremely important" to remain indifferent to critical comments.
"I never try to defend myself or the trade because no matter how right you are, you end up looking bad," she says.
"Anyway, as the saying goes, the customer is always right."