To publish a novel, first you must finish it. Only Stephen King can submit a proposal for a novel before it is actually complete (and I'm sure that he outlines his books at the very least before submitting such a proposal).
Finishing a novel is much harder than starting one, and it is easy to get bogged down. Some writers hate beginnings, some writers hate endings, and some hate middles. Usually, my own novels are very strong in the beginning and end portions, but the middle is only a tenuous thread, easily breakable and usually tangled. Right now, I'm in the middle of
The Witch's Daughter, and it's not the most exciting part of the book to write (although I hope that it will be exciting to read).
To motivate myself, I have spent time on the beginning and end of the novel as well, typing out pieces of the middle in between so that I don't get overwhelmed. My middles also tend to have the most sex scenes and romantic bits, because the end and beginning are usually more plot-focused. Sex scenes are a great way to distract myself from how much I hate writing middles. And boy do I hate middles!
So think of ways to spice up your middle if you find yourself stuck. Although my novels usually have sex, many novels do not, and there are plenty of other ways to keep the momentum moving forward. Introduce a new character, perhaps one that is not clearly good or evil, for the reader to wonder about. Insert a natural disaster, an attack, or an invasion. If you are writing in a modern-day setting, the attack can be a verbal one or some kind of fight. Have your protagonist injure themselves, have the villain make an appearance, write scenes in which a side-character becomes more prominent and begins acting mysteriously, reveal a secret about the protagonist's past. Just do something, or you will get bored with your writing, and when a writer is bored, the reader can tell. Stave off boredom at all cost by introducing the unexpected.
Although it can be tedious, plotting out your entire novel from beginning to end is also a great way to keep yourself on track. You can do this in several ways. First, write a summary. Try reading the jackets of a few books in your room to see what I mean. It should only be a few sentences that clearly state the main conflict of the book, introduce the protagonist, and leave you interested. You can choose to include your ending, or not. Then, use that paragraph to write a synopsis. You can even use this synopsis later to submit your novel to a publisher! A synopsis should be one page, single spaced, and outline all the scenes you want in your book. You don't have to finish your summary right away if some of the spots in your novel seem unclear. This is only the planning stage. You can add to or delete from this summary later. However, it will outline the spots that you need to focus on so that you can smooth them out.
These summaries are always written in the PRESENT TENSE. For example, my summary for The Second Sister begins: Eleanor Sandleford is thrown into a volatile situation when her father, Lord Roland, marries Lady Kingsclere. Although her new stepmother appears friendly, Ellie notices tension between her two stepsisters, Luciana and Belladonna.
You get the idea.
If you can't be bothered to write a summary when you get stuck, try doing an outline instead. Just use some bullet points to list scenes and characters that are important in your novel. You can organize this outline any way you like, and no one has to see it but you. Just make sure that you can understand what you mean when you go back and read it later. (I admit that I have occasionally referenced plot ideas in these quick outlines that I later forgot).
The most important thing to do is keep writing. Even if you feel like you're at a boring part, keep writing! You can always delete or brush up that part later if it seems sluggish or lugubrious. Just keep pushing forward, and eventually you will get to a more interesting part.
