Read popular romance novels. Bestselling romance writer Morgan Leshay urges would-be writers to read the current romance novel bestsellers to get an idea of what type of novels are popular. Of course, tastes change, and what is popular this year, may not be next year. However, you need to be familiar with romance literature in general.
Read articles on writing romance novels in such magazines as "The Writer" and "Writer's Digest" and search online for specific information on writing love/romance stories. Occasionally, there are online chat rooms where romance authors congregate and to answer questions and offer advice.
Write a one-sentence description in 15 words or less that describes your love story. This will help you focus your thoughts on what you want to write and serve later as a quick selling tool for the book. Now expand the sentence into a paragraph detailing the story's set-up, primary conflicts -- three is often suggested -- and the ending. A three-act structure -- the most common type of structure in movies, scripted television programs and most books -- has a major conflict at the end of each act. Ideally, the conflict should keep the would-be lovers apart. In the second and third cases, the conflict is often the result of the heroine's attempts to fix problems.
Create your characters by picking names and then writing a one-sentence description of their role in the story. Write down the character's motivation, goal, conflict and epiphany, or the thing that will make them change by the end of the story. Now, write a paragraph about each character so that you get to know them. As you write the book, other character details will do doubt occur to you. Some writers create character charts for each character.
Write a plot synopsis using the character sheets you have created. This will provide you with the overarching plot plus some subplots and help you find holes or problems with the plot structure. Some writers will create a complete outline, chapter-by-chapter, while others simply write down high points and low points and allow the story to evolve as they write.
Research the information that you need for your story. If it is an historical novel then, of course, you will need to find details on the period and events of that time. You should find descriptions of clothing, housing and other items important to day-to-day life in your period. Often, the social histories of a given period are excellent sources.
Write your love story. You know your characters, you know your story and you have your plot. Begin with chapter one and proceed. Due to the preliminary work you have done, you will likely find that you can write the rough draft quickly. By the time you finish it, you will have the beginning of a good book. Editing and revising is crucial to arrived at a finished story that will may grab the attention of an agent or editor.