The book you are writing should be about something that you want to write about, not something your friends or family tell you, you should write. You should only write about what you want.
Your book (or novel) should also be something you really want to write. So when you wake up in the morning you're excited about writing. And you have that craving to write.
The first book I wanted to write was going to be a vampire novel (and yes I know it's past tense). I wrote about 40 pages, took me months, but I started to feel really bored with it. I've had problems writing and finishing books before. I'll get 60 pages into a book, and get bored with it and end up not continuing it.
Anyway, so I got bored writing the vampire book. But then I got another book idea. I finished this book in 7 months. The next one I finished in about 4. And then the final book in the trilogy took 2 months.
I really enjoyed writing that trilogy. It was a blast coming up with more and more ideas to throw in.
When you begin to write a book it's okay not to finish it. You can wait a while, get another book idea, and start writing that idea down on paper. Your book can be about anything! You just have to use your imagination.
If you have an imaginary world you slip off to when your bored, you could write about that. Or you could base your book about a dream you had.
Like Stephenie Meyer:
The author of the New York Time's bestselling series, the Twilight Saga.
She got the idea for Twilight (the first book in the saga) from a dream she had. She had a dream about a boy and a girl lying in a meadow and when she woke up, she wondered what kind of relationship these two people had. What their story was. And dam! The book Twilight was created!
A dream! This woman had a dream and wrote a book, and then ended up writing 3 more books after Twilight! She became a New York Time's Bestseller!
This is possible. Your book could become a NYT bestseller! All you have to do is write the book, copyright it, and either self-publish it, or publish it the classic way!
Get started! Hope your New Year is awesome!!!! And filled with writing and success!