Writing and finishing a novel is only the first step on the long, hard road to publication. For an unpublished author, it is a very difficult process indeed. There are dozens of different publishing options, and many decisions a writer needs to make.
First, it's important to understand what style and genre your novel falls under. Mainstream fiction, literature, thriller, paranormal, romance, suspense, young adult, mystery, western, science fiction, horror, action-adventure. And these are just some of the styles to indentify your work. Within these genres there are sub-genres.
You may have a young adult novel which is also a mystery -- Hoot by Carl Hiaasen, or a fantasy/paranormal -- all the Harry Potter books by J.K. Rowling
Or a romance that is also a suspense novel -- I'm watching You by Karen Rose
Or an historical that's also a romance -- Unmasked by Virginia Henley
Then it's a matter of researching literary agents and publishing houses to determine the best fit for you and your book. This is a time-consuming, but necessary job for anyone interested in getting their work published. It's a waste of your time and the editor or agent if they don't represent or publish your genre of writing.
One excellent way to possibly get in front of an editor or agent is by entering contests. There are hundreds of contests out there for fiction writers. In the romance writing world, almost every chapter of the Romance Writers of America sponsors a contest. Usually the final round judges are from some of the top publishing houses in the industry.
The Mystery Writers of America and the Sci-Fi Writers of America probably have simliar opportunities as well. Being a writer of romance, I don't know about their organizations first hand.
Check the internet for any fiction writing contest opportunities.
Just remember to do your research. Make certain the organization hosting the contest is legitimate, that the contest offers your genre of writing, and that the final editors are from a publishing house where you would want your work published. Also make certain the price is right. Most contests charge a fee to help raise money for their chapter or organization. However, some of them also offer a critique with your entry. This is a great tool to becoming a better writer and enhance your novel.
Every year, in the fall, The Romance Writers of America hosts the Golden Heart Contest, a national fiction romance writing contest for unpublished authors. I plan to enter this year with my manuscript Summer Light. :)
Wish me luck!!