Good tension begins with good character dynamics.
In both erotic and romantic writing, it is important to consider the way the characters are going to interact. Ask yourself, “What is it that attracts your protagonists to one another? What could potentially keep them apart?” You want the romance to build gradually, waxing and waning in a natural progression, while also creating obstacles that threaten to destroy the relationship before it has a chance to climax. Don’t be afraid to tease your audience; you want your readers to crave satisfaction just as desperately as you want your characters to crave one another. If you give in too quickly, you might make later interactions less satisfying—but if you hold off for too long, you’ll lose your readers’ interest.
Balance is the key.
Just like any good story should be divided into three “acts,” a good erotic romance should be divided into a number of “episodes.” In a typical plotline, Act I introduces the characters and whatever initial dilemma they are to overcome, Act II brings added intensity to that dilemma (often with the overcoming of the first dilemma, only for a larger one to arise in its place), and Act III moves the story to its climax and conclusion. With romantic and erotic “episodes,” the romantic and/or sexual tension should rise and fall around every thirty to fifty pages. Just like with the necessary resolution and additional dilemma found in the transition between acts, one should strive for romantic or sexual dilemmas between these episodes, offering resolution—or even some kind of minor release—only to build the tension even higher than before. Mistaken identity, misconstrued words and/or actions, quarrels and reconciliations, and love triangles all work well to add to the building and dropping of romantic and sexual tension.
Think of the building of romantic tension as written foreplay.
Words are powerful tools; use them to your best advantage. Play with your readers’ senses. Use words or phrases that appeal to the body or further arouse the imagination. Your wordplay need not be overtly sexual to be sensual.
Consider the following poem:
A gently laced chain of words
awakens every sense;
colorful, sweet, musky, hard,
and symphonic offering, aching, needing.
The hot, dew-wet red rose
smells the fragrant hard wood
that penetrates deep into the earth,
expanding, tasting her soil,
and dancing to the sonata in the wind.
The above words use imagery in slow, sensual steps to build its readers. If the poem were to continue, it is safe to say that the sexual tension would rise and fall through a series of several more stanzas, with the final lines bringing both the natural figures and their audience to climactic release. Give your readers prose that takes them beyond their own bodies, while at the same time offering a holistic, full-body experience. Tantalize their minds, make their bodies tingle, and then tease them with a twist of heartache or disappointment, only to build them and their expectations even higher than before.
And then, around the same time you’ve reached the climax of Act III, give your readers what they’ve been waiting for—sweet, beautiful, sensual release.