Anyone who's read my writing knows that I'm not one to stay in one genre. While it's true that the fastest way to build your career is to be known in one genre such as paranormal romance, I'm not convinced.
I've written contemporary suspense erotica, dystopian romance, and those previous books all received a bump in sales when I put out my fantasy erotic romance. So, there are ways to write across genres.
The most important thing when writing in more than one genre is to define your niche market for that specific book. What are the fundamentals that comprise your book? For example, in Love's Demon Ways, I tackled the elements of a woman having a broken heart and being reckless by having a one night stand. What woman can't relate to this behavior on some level? Therefore, I can specifically market this book not only toward paranormal romance readers, but single women and erotica readers as well.
Writing across genres does take more work and effort than staying in one genre, but if this is who you are, then the readers will follow for love of your voice. Let's take romance readers for example. I would venture to say that most do not read in one genre of romance. I love reading Gena Showalter's books paranormal series as well as Lori Foster contemporaries.
Writing across genres has another benefit. You're able to reach more readers. Market elements of your book to specific groups in order to draw them in. While readers of true life animal stories might not read a romance, a romance book containing animals they might give a try. Be bold and market to those readers that might otherwise pass over your book. Word of mouth is the best marketing tool. Especially, when you've introduced a new reader to your work and they never would have thought to read your book in the first place. They're excited and want others to know what they've discovered.
What's important is to entice the reader and deliver on your promise of what the book will give them. Romances, we generally want hot sex and a happily ever after or happy for now book. Romance authors are marketing; love, passion and hope, so we must deliver on those feel good feelings.