The 48-year-old presented his first book The Liar on Thursday, which recounts the adventures of a millionaire antiques collector who clashes with the Vatican while hunting for stolen manuscripts.
"What I most love about writing is the process of preparing for it," Mel, whose side play Real Madrid at the Bernabeu on Saturday, told a news conference.
"The novel's plot reflects my passions, the everyday things I like," he added.
"It helps me to relax and between pages I might think of a way to stop [Real forward] Cristiano Ronaldo."
Mel said the novel, which will go on sale on October 19, had taken him four or five years to complete and he was now working on a book about 17th-century Spanish painter Velazquez.
"I never though I could write a book," he said. "It's something I do in the free time football allows me. The only thing I ask is that people have as much fun [reading it] as I had writing it."
Promoted Betis made a fine start to the season on their return to La Liga. The Seville club won their first four games but have since slipped up in their last two and sit in seventh place, two points behind pacesetters Barcelona and Levante.
