Everyone's giggled over a romance novel a time or two--paged through it, picked out the love scenes, and snorted. Since the 1970's when popular romance writers such as Kathleen Woodiwiss, Johanna Lindsey and Rosemary Rogers pushed the spiciness envelope of historical romances, love scenes --or sex scenes, as they're sometimes called-- in romance novels have become an essential part of the genre. Some writers find hot love scenes easy to write, others find them a challenge. Here's how you write the hot love scenes romance readers will love to read...and kids will love to giggle at.
Write the appropriate love scenes for the subgenre you're writing for. Educate yourself by reading. Learn that category romances vary widely in the types of love scenes they feature; Harlequin Romances are sweet, while Harlequin Blaze are hot and spicy, and Harlequin Spice are really, really spicy. "Romantics" is a genre that blends hot romance and erotica, and some consider it within the purview of the romance genre. Learn the conventions of contemporary romances, historical romances, and futuristic, fantasy, and paranormal romances. Read publishers' guidelines to find out how hot they're buying romance books these days.
Write love scenes consistent with your writer's voice. Many new writers of romance novels assume that to write a hot love scene, they must indulge in purple prose like, "Her voluptuous bosom heaved with torpid passion." Uh-uh. Write about the sex and lovemaking in your natural style of writing.
Think quality over quantity. One hotter-than-hot love scene at the end of the novel can sell a book faster than five love scenes that are yawners, written without real passion. Gratuitous love scenes put in for filler only disenchant your reader.
Situate love scenes where they fit best in the story. This isn't as easy as it sounds, and it takes some intuition. Novels have a rhythm; action builds and then peaks and then eases off; same with tension and pacing. Romance novels feature an escalating series of such peaks, culminating in the big climax at the end. Your love scenes will go right at the top of some of those peaks. Puns intended...
When you write your love scenes, make sure your characters act in character. Letting them act out of character just so they can display the expected lust for a love scene is part of what brings on those juvenile giggles. Think about your characters' personalities and have them behave only slightly more outrageously than they would if they were real people...exaggerating just enough for fiction.
Write passionately. Well-written, sensual love scenes are not about body part a being inserted into body part B, but are about the senses and thoughts and feelings of the characters. A touch of the wrist can be achingly sexy to read about; so can oral sex; so, in fact, can a description of a man's fingers. But avoid mechanical descriptions of sex; your reader could have consulted a sex manual if that's what she wanted. Concentrate on describing the feelings and sensations involved.
Avoid falling back on overused clichés in writing love scenes. Though it's nearly impossible to eliminate all clichés in a romance novel, try to make every phrase as original as you can. Your jaded readers, who are likely to have read hundreds, if not thousands of love scenes by the time they pick up your book, will thank you. Know that far too many things tend to swell, throb, pulse, ache, writhe, flush, and pant in a romance novel, so try to come at what's happening at a new angle that your reader's not expecting. Yes, you'll be describing certain basics: kissing, touching, foreplay, sex. But remember there are an infinite number of ways to describe everything from a gentle kiss to sexual intercourse. The obvious advice applies here: be creative.
Become an expert. If you don't have a lot of direct experience with the kind of sex that you're writing about, then do your research. There are plenty of books on sex and lovemaking available. Write love scenes that convince your reader you know more than they do about lovemaking. Love scenes are part of a romance writer's repertoire.
If I've left out any steps that would help you, tell me in the comment's section and I'll add them. Good luck with your romance book!