Check with well known romance book publishers. Checking with the big name publishers will give you an idea on what types of romance novels are selling and what they are looking for. Harlequin, Avon and other popular romance publishers supply a wealth of writing and publishing tips on their websites.
Make sure they're accepting book submissions. When you're attempting to get your book published, you need to read the submission guidelines before you send off your manuscript. Each publisher has different guidelines concerning format, romance genre, submission departments and book lengths.
Query before you send. Publishers have different rules regarding unsolicited manuscripts. Some will want entire books, while others want you to send a partial manuscript or query first. If you do not follow their instructions, your romance novel may not even be read by a publisher. Always follow their rules.
Think about a literary agent. Some publishers will not consider new writers unless they are represented by a literary agent. Do your homework before getting an agent. Reputable agents will not ask you for up-front money for costs and such. The Association of Authors' Representatives or AAR is a great resource for finding reputable literary agents.
Try self-publishing. If your response from publishers is less than stellar or you want to get your romance novel published right away, you may opt for self-publishing. There are publishers and printer online and off that will help you publish your romance novel. Be aware that with most self-published books, much of the promotion is left up to the author.