Deciding to adapt a book into a TV series is easy. Figuring out how to do it is a lot trickier.

Among the many questions creative teams need to resolve: How many episodes should there be? Does the story need to be updated? Should they try to broaden it to attract an even bigger audience? How closely should they follow the book?

After all, built-in book audiences are a large part of their appeal as adaptation material. Deviate too far from the novel and its core audience might cry foul.

Having recently adapted a beloved movie for TV, Warren Littlefield knew the inherent risks, and challenges, to doing the same for an iconic novel. But he was blown away by Bruce Miller’s take on Margaret Atwood’s “The Handmaid’s Tale,” so he boarded the TV adaptation, one of several lit newbies this season along with “Big Little Lies,” “American Gods,” “13 Reasons Why” and “I Love Dick.”

Littlefield’s first order of business: Persuading “Mad Men” and “Top of the Lake” star Elisabeth Moss to take the plunge with him on Hulu’s highest-profile series to date.

“I had hundreds of emails with Lizzie and lots of phone calls,” says Littlefield, producer of FX’s Emmy-winning “Fargo” adaptation. “I said, ‘I’ll do it if you do it.’”

She agreed and then the real work began: realizing Miller’s vision for the adaptation. Early on, Littlefield says, you get a glimpse of what the show might be, but “then it’s up to you to make hundreds of correct decisions.”

When creating an alternate world like Gilead, you have to make sure it’s still believable, he points out, crediting “Game of Thrones” showrunners David Benioff and D.B. Weiss for doing just that on their adaptation of George R. R. Martin’s fantasy novels.

For “Handmaid’s Tale,” that meant creating a world that seemed modern but off-kilter and repressive. Modern references like Uber were added to the script, and inordinate care was taken while selecting the handmaid’s otherworldly garments, which evoked the Puritan era.

“The pressure was on us even more after the election with the alt-right, and for women’s rights.” Warren Littlefield

“We looked at 30 different bonnets and wings,” he recounts, wondering, “will it be like ‘Flying Nun’ with a laugh track?”

In another production decision, an older Boston grocery story was rejected because the lighting did not seem modern and fluorescent enough to resemble the average viewer’s supermarket. That similarity helps make the market seem familiar until viewers notice the minimal offerings and men patrolling the aisles with rifles, he explains.

“It is New England in the fall. It is Boston. It is Cambridge,” he says. “It is clean. There are hybrids. But you have the tyranny of Gilead, the sexism, the fascism, that is a nightmare. Building that world was a challenge.”

When Reese Witherspoon and Nicole Kidman’s production companies pursued the rights for Liane Moriarty’s “Big Little Lies,” then in galleys, they weren’t even sure how they wanted to adapt it. But they quickly ruled out film, says producer Bruna Papandrea, who developed the project with Witherspoon at Pacific Standard, along with Kidman and her producing partner Per Saari at Blossom Films.

“Nicole felt like film would short-change the story,” she says.

Neither company had produced serial TV before, so they had to figure out their strategy, asking themselves how many episodes the book should be. TV creator David E. Kelley determined the answer while adapting the Australian setting to upscale coastal Monterey for the HBO version.

“David was always adamant that the material would tell you how long it was,” Papandrea says.

The series was originally intended as an eight-episode limited run, then cut back to seven because Kelley felt that worked better, the producers say, quickly adding that HBO was very supportive of the decision.

Kelley also modified elements from the book: Witherspoon’s Madeline is now harboring guilt over an affair in a twist developed out of conversations between the actress and Kelley. Not only did it make her character more interesting, the producers say, but it also added another element of mystery to the plot.

The TV version of “Big Little Lies” also devotes more time to the children and husbands than the book, while painting Alexander Skarsgard’s abusive Perry in a more nuanced light. Meanwhile, director Jean-Marc Vallee played up environmental elements and music, giving the series a stylish look.

All these elements helped the series attract a broader audience than otherwise be expected from a bestselling book with such a strong female following.

“I was relieved that the series was embraced the way it was,” Saari says. “For the most part it was really positive. You never know with a book that has such a strong fan base how it will go.”

He credits Moriarty, a fellow Australian, with Papandrea and Kidman, for laying all the groundwork.

“Her writing is so deceptive, nuanced and complex because it’s so accessible. She created an amazing blueprint beyond a blueprint.”

“American Gods” showrunners Bryan Fuller and Michael Green had both adapted books for TV before — Fuller with “Hannibal” and Green the Bible, no less. The long-time producing pals, who met while working on “Heroes,” found Neil Gaiman’s book intoxicating.

Reese Witherspoon’s company helped develop HBO’s “Big Little Lies.”

The big challenge, the pair says, was to exercise restraint in telling the otherworldly tale of gods and miscreants. Originally they planned to adapt about a third of the book for the first season of the Starz series, but didn’t quite make that goal.

“Really for me, it was absolutely wanting to share it,” Green says of his enthusiastic approach.

But the producers didn’t want to get hung up on re-creating the 2001 novel they loved.

“The lesson I learned from adapting ‘Carrie’ was the danger of being too fidelitous as opposed to editorializing,” Fuller says. “ ‘Hannibal’ was much more editorializing and ‘American Gods’ was somewhere in between.”

They expanded elements from the book, further developing the Laura Moon character, for example.

“We were wondering aloud to each other what they were doing when we weren’t reading about them on the page,” Green says. “That’s where the fan fiction comes in.”

The showrunners aren’t too concerned about fan grousing, good-naturedly referring to the “rabid subsection” that show their affection through dissecting their favorite shows online.

And in any case, they’ve been in close touch with Gaiman throughout the adaptation process and describe him as very amenable to almost everything they have run by him.

Likewise, the “Handmaid’s Tale” showrunner has been conferring with Atwood as he adapts her book into its TV form.

“She loves the process,” Littlefield says, noting that she made a brief cameo in the first season.

For him, that’s an encouraging sign that the adaptation process is on track. “It’s similar to ‘Fargo.’ The movie is one work of art and the television show is another.”

The project gained added resonance after Donald Trump won the presidential election, sweeping in a new era of regressive policies that threaten women’s rights, creating an atmosphere that didn’t seem so far from Atwood’s dystopian Gilead.

“The pressure was on us to live up to Margaret’s book,” Littlefield says. “But the pressure was on us even more after the election with the alt-right, and for women’s rights, with Planned Parenthood under attack.”

Other lit adaptations have run into even more turbulence, underscoring some of the inherent risks in such projects. Netflix’s adaption of Jay Asher’s YA book “13 Reasons Why,” for instance, has drawn fire for the way the series tackles teen suicide, but it has been renewed for another season, prompting speculation about what storytelling angle the series would follow.

Unlike the 1970s and 1980s, when networks regularly turned bestsellers such as “Rich Man, Poor Man,” “The Thorn Birds” and “Roots” into miniseries, today’s producers are taking an increasingly open-ended approach to the literary material.

Miller and the “Handmaid’s” writers are developing season two, which will go into production in the fall, once again in New England.

As the series moves beyond Atwood’s prose, it will explore areas referred to in the book, but not described in depth, such as the Americas.

“If we get this right, there is so much to explore,” Littlefield says.