It's one of the most common problems writers come up against: I can't finish anything. It used to be true of me, too, until I got really excited about my writing a few years ago. Since then I've completed four first drafts and many more revisions. So I would say that if nothing else, I'm good at finishing books. ;)
I thought I'd write up some advice for how you can finish your books, too. I really want to stress the fact that not all of the ideas will work for everyone, and in fact some of them might contradict each other. But take a look and consider whether something on this list might be useful!
1. Make any or all of the following promises to yourself:
-I will not revise until I have finished the first draft.
-Nobody except for me will ever lay eyes on the first draft.
-I am not allowed to reread anything I've written until I finish the first draft.
The point of each of these is to keep yourself from getting caught up in how bad your first draft is. If you're like me, you find much of what you put down on the page to be horribly embarrassing, and so that second promise is in order. Or maybe you're not yet worried what others think, but you keep coming up with ideas for how to make what you've already written better. But you don't want to get stuck rewriting the beginning of your book forever. Keep a sheet of paper or a text file where you write down all the ideas you have for revision, from big to small. Then leave the first draft be until you're done with it.
2. Reevaluate what you've chosen to write about.
One of the best pieces of writing advice I've ever heard is to write what you're passionate about. When I'm working on a book, I get obsessed with it. I think about it day and night and I can't wait to work on it. And that's because I write about people and stories that just make my heart sing!
If you aren't getting excited about your stories, take a chance and write about what really interests you. Even if you don't think it's the right genre, or you don't have the right expertise for it, just try it!
If you have the problem of developing a new obsession faster than you can finish writing about the old one, try to incorporate your new interest into your WIP. If necessary, add a new character to keep things interesting.
Above all, don't waste your time with things you "should" be writing about. Write what you want.
3. Skip the boring parts.
If it's boring to write, chances are it will be boring to read. Mundane stuff that's necessary to move the plot forward can often be taken care of with a splendid item known as a transitional sentence: During the next three months, Jessica got used to her daily routine. Bam, you're done, now back to the exciting scenes.
4. Skip difficult scenes if they're giving you trouble.
Sometimes you have a scene that's not boring, it's just hard to write. Don't let yourself get hung up on a single scene. I'll usually give a tricky scene a couple tries spread out over a couple days, and if I'm still not moving forward, I skip it. More often than not, it's much easier to finish once I have some perspective on the other side. Just make sure you write yourself a note or put in a placeholder so you don't forget and then confuse yourself when revising!
5. Visualize and get excited.
This one should be done sparingly, but it has its uses. Daydream about finishing your book. Imagine how great it will feel to write "The End." Plan how you're going to print and bind the manuscript. When I was slogging through my first book, I called around to different office supply stores to find out what my cheapest option would be.
It's not good to daydream to the point that it's keeping you from getting actual work done, but a little bit can be a great source of motivation.
6. Take a break, but make a date to come back.
This one's risky, and I suggest only using it as a last resort when you're just not sure if a story is going to work out. If you are completely and totally stuck, put the project away for a while and promise to return to it after two weeks, a month, six months, whatever works for you. You might work on something else during that time, or you might just read and inspire yourself.
Sadly, some stories are just doomed to go nowhere. If you come back after your break and still can't make things work, it might be time to move on. But sometimes a break can offer perspective, new ideas, and an absence-makes-the-heart-grow-fonder effect. I took a month long break in the middle of the book that ended up snagging me an agent, so there's proof it can have a happy ending!
If you're chronically abandoning books, however, you might not want to risk this one. Remember, it's a last resort.
7. Set specific goals.
Pick a word count you're working toward, and decide how many words you can do per day. If you have a problem meeting goals, rework them. It might sound nice to write two thousand words a day, but if all you can regularly get to is 250, then make your goal 250. Goals should hold you accountable and stretch you a little bit, but they need to be attainable or else there's no point.
8. Change up the order in which you write.
During my first few attempts at novel writing, I made a fatal mistake: I skipped around and wrote all the best scenes first. By the time they were out of my head, I'd dumped everything that was compelling to me about the story, and I couldn't finish it.
Now, by "best" scenes I don't mean "only exciting scenes." As I said above, you should probably skip boring stuff anyway. What I'm saying is that if you have a cool scene in your mind that takes place later on in the story, write to that scene. Come up with cool stuff that will get you from point A to point B.
Alternatively, if writing books in order makes you lose focus, try something else. Write your book backwards. Write a scene from the beginning and a scene at the end, then go back and forth until you meet in the middle. Mix it up until you find something that works.
9. Don't tell people what your book is about.
You've got a story you're excited about? Good. Is it so awesome so you want to tell everyone you know about it? Even better. BUT... don't do that.
Writing is storytelling. When you're writing a book, you've got a story to share with people. Don't spill it prematurely, or you risk losing the drive to put the words down on paper.
10. Just... finish it.
Writing is an art, not a science, and there is no foolproof way to guarantee success. It's also not a magical skill you're born with. Like most anything else worth doing, it takes time, practice, and determination. So stop making excuses, and go finish your book!