After a few years with her husband, Natassia Miller was looking for ways to spice up the couple’s sex life. She decided they should give sexting a try.

“Amor,” Miller, 34, wrote one afternoon. “I miss you and can’t wait for you to come home tonight.” She described what she would like to do with him later that evening in great detail.

Then she waited nervously for his response. “Great,” he wrote.

“That’s what he’d say if I told him I got his dry-cleaning,” Miller says.

Ah, the joys of married sext.

Sexting—or sending sexually suggestive messages—is a good baby step to relight the flame in a long-term relationship, sex therapists say. It can help couples practice communicating about their desire, building erotic anticipation and reinforcing their bond, even when they are apart.

Yes, talking about such intimate things requires you to be vulnerable in front of the person you love most in the world. For couples who spend most of their time talking about kids, work or the logistics of home life, this can be downright mortifying.

But it’s worth it! Research shows that it’s important for couples to communicate about sex . A review of 93 studies, published in 2022, found that those who do so improve both their sex life and their relationship.

Sexting doesn’t even have to be X-rated. Talk to your partner about what feels comfortable and give yourself some time to get used to it.

Not convinced? I get it. In reporting this column, I heard about a couple who sexted each other without realizing their teenager was using the family iPad, where their messages popped up. A woman said she was happily reading in bed one night when her air conditioner repairman messaged her: “I hope you’re naked and waiting for me when I get there.” (He apologized profusely—then gave her a discount on her next repair.) Others reported accidentally sending texts to a client or their boss.

Often, it’s the tech, not the talk, that turns people off sexting, says Michelle Drouin, a professor of psychology at Purdue University, Fort Wayne, who has studied the topic. They worry Big Brother is watching. Or that their kids will find a sexy exchange on their phone.

Or that they might take a sexy photo in a white T-shirt with nothing underneath for their husband—and accidentally send it to their father-in-law, like Dana Nichols did.

She and her husband, Wallace J., were trying to get pregnant, years ago, when she sent the text. “It was meant to get sexy time going,” says Dana, 55, a hospitality consultant in Louisville, Ky.

But her husband and her father-in-law had the same name, and she hit send before noticing that she was sharing her photo with the wrong Wallace.

Her husband says his dad forwarded the photo to him, with a brief message: “I think this is meant for you. Glad things are going well there.” He replied with one word: “Thanks.”

There are good ways to explore sexting in a way that’s hot, rather than humiliating. Here’s a primer.

1. Talk about it first.

Make sure both you and your partner are comfortable doing this.

Discuss when to send and receive texts; whether you prefer words, pictures or both; if you’re OK with explicit content or want to stick with merely suggestive; how soon to expect a reply.

2. Be careful.

Choose a messaging platform where you don’t talk to anyone else, says Shadeen Francis, a certified sex therapist and marriage and family therapist in Philadelphia. She recommends the Signal app to her clients because it is end-to-end encrypted.

Send your partner only sexy messages there. No one wants to be talking about romantic bubble baths one minute and groceries the next.

Don’t text from your work phone.

And please—I beg you—double check who you’re sending it to.

3. It doesn’t have to be X- or even R-rated.

Some people prefer their sexting to be explicit. They like to tell a story, express a wish or give instruction.

But sweetness counts too, Francis says. You might try: “I would really love to kiss you.” Or: “I have been daydreaming of your smile.”

Be creative. Music, poetry or a romantic photo can all get your idea across.

And if you don’t know how to answer? Francis recommends you respond with a simple: “I love that you are thinking of me” or “tell me more.”

4. Sexting isn’t a contract to have sex.

It’s its own reward.

Letting go of the pressure to follow up with sex later will free you up to take more opportunities to connect, Drouin says.

5. Emojis are your friends.

People who use emojis—those little smiley faces and other images you use to express an idea or emotion—tend to have more success in their intimate relationships and have more sexual intimacy, according to research from the Kinsey Institute at Indiana University.

Find the eggplant emoji (look it up) cringey? Try a kiss, a wink, or one that nods to an inside private joke.

“You just want to be sure the other person understands,” says Todd Baratz, a certified sex therapist in New York.

6. Give yourself time.

Think of it like riding a bike: It may take a few tries to get the hang of it.

After Miller’s husband sent her a one-word reply to her message, she asked him if he was comfortable sexting. He said yes—he just hadn’t done it before so wasn’t sure what to say.

So Miller, who runs a sexual wellness company, decided to take the initiative. She started sexting her husband several times a week.

One recent Friday night, she sent him a series of racy texts while he was at a poker charity event.

His reply this time? He was ordering an Uber to come home immediately.

Write to Elizabeth Bernstein at Elizabeth.Bernstein@wsj.com