Come up with a high-concept premise for your romance. High-concept means something that can be expressed succinctly yet paints a vivid image in the listener's mind of a story that is new and different from anything else out there but touches on something already familiar. In her article on high concept, Misa Ramirez identifies the book "Cinderella Lopez," by Berta Platas, as high concept because it can be summed up simply as a fairy tale with Latin flavor.
Consider any comparisons that can be made between your story and works in the popular realm. In the example given above, the high-concept premise involves relating the story to the popular fairy tale "Cinderella."
Identify the main character, the character's goal and the main force that will block that goal over the course of the story.
Express your premise in one or two sentences, 25 words or less. The more you can refine it, the easier it will be for you to focus on this core element as you write, and the less tempting it will be for you to drift off into tangent story lines that weaken the plot.
Pick a hero and a heroine. The story is nothing without them. They need to be strong, larger than life and, above all, sympathetic, even if they do the wrong thing. They do not need to be perfect--in fact, perfect is boring. The reader must be able to identify with them in order to be interested in following them through the story. Give them flaws, but also give them something admirable.
Avoid stereotypes. Not all heroines need red hair and green eyes. Not all heroes should be dark haired with blue eyes. In fact, physical appearance should be the last of your concerns. Dig deeper. Think about what makes them who they are inside. What is their "character," their values, their thoughts and feeling about the world around them?
Develop a history for each character. Writing this out can help you learn more about them. Give them a past, a childhood, things that helped them become who they are at the time of the story. You don't necessarily need to reveal all of what you come up with in the story. However, it colors their character, and it will help you, the author, understand them more and understand how they should react to situations in the plot.
Develop strong conflict between the hero and heroine and within themselves. Without conflict there is no story, because if everything goes swell for the characters all the way through, why would someone bother reading about it? It's the struggle that will keep the reader turning the pages.
Put your hero and heroine at odds with each other over something that has nothing to do with their romance. The romance is what develops while they are battling this other conflict. The tension needs to last the entire book, so be sure you don't make it something that a nice sit-down over a cup of coffee can solve. The best conflicts arise from two people seeing the world differently and one of them having to change in order for their romance to succeed.
Plan your hero and heroine's character arc, how they grow and learn over the course of the story through the events of the plot. They start the story with one way of thinking, but when faced with conflict, they need to rise to the challenge (several times), and this changes something inside them. They learn from their struggle, and they come out better for it.
Keep raising the stakes in the conflict. Think of how the television show "24" is structured. Poor Jack Bauer never gets a break. Once he solves one problem, before the end of the episode, another pops up and it's worse than the previous one. Do the same with your novel. No explosions are needed, but things the hero or heroine care about need to go from bad to worse before they have that "ah-ha" moment, learn something and find a solution to their problem.
Do not go easy on your characters. Human nature makes us want to reduce conflict when we can, to find a solution and reduce tension. You need to ignore this instinct when writing a romance until the end when everything reaches the happily-ever-after. The reader wants to see the characters struggle to find that happiness. Only then will the reader perceive it as well-deserved.
Pick a setting for your story. Try to make it unique.
Make the setting integral to the story. If you can go through your book set in Seattle and replace the city with Boston and not affect your story line at all, then the setting is not contributing what it should to the story.
Think about how the setting affects the characters and bring that to the story. A native of the area you pick, for example, will have a different perception of the place from a newcomer.
Don't force it. You'll notice that "characters" is higher on the list here. It's fine to come up with the inkling of a plot first and think about what characters fit it best, but when it comes down to mapping out the details of the plot, define your characters first, then let them lead the way.
Allow characters' decisions, in the face of adversity, to drive the plot forward. Think of it this way: A character meets a situation, encounters a problem (conflict) and then must make a decision. That decision should tell you what happens next. If you force decisions on the characters that don't come from within them, you'll risk a hero or heroine acting against character, which comes across as illogical and confusing.
Remember to up the stakes in the plot. These decisions that lead to the next plot point should make things worse until the big "black moment" in the plot where things are as bad as they can possibly be and the only way to go from here is up, if the character is willing to change.
Plan the "black moment" in the story. In a romance, this is where all seems lost, the hero and heroine can't possibly ever be together because of what's happening. It's your chance to really keep the reader on the edge of the seat wondering how it will all work out.
Give your hero and heroine a happy ending. In a romance this is a requirement of the genre. Anything less and the book is not a true romance, but more likely a women's fiction story or mainstream novel.
Do not kill off your hero or heroine. Bittersweet endings are not for the romance genre. Romance readers come into the story with certain expectations. They know that no matter how bad things get in the story, it will always work out in the end.
Don't wrap everything up so tightly that it's unrealistic, but don't leave any obvious loose ends unless your book is part of an ongoing series and the loose ends will be addressed in the future. At the very least, the plot involving the hero and heroine must be resolved satisfactorily and they must be together.
Don't feel you need to marry the hero and heroine off. Not all romance publishers require marriage at the end. Check the publisher guidelines, read several books in the line you think your story fits and see how the endings are done.
Write as much as you can as often as you can.
Practice. This is the only way to become a better writer. You can read all the how-to books and articles you want, but the only way your book will get written is if you sit down and put the words on the page.
Don't make excuses why you can't write. If you want to write, you will find the time. A few minutes here, a few minutes there, it all adds up.