Passion. Without passion about the subject, you won't write the book.
Great ideas come from the most innocuous places. Don't expect your idea for a story to come flowing out all at once. Start with anything you like. Sometimes I listen to music and imagine a place or a scene that the song would play over. Also, you should never be afraid that your ideas are too unoriginal. You're lucky to come by one truly original idea in your lifetime. Just write about what you know.
write about my crazy drama life
i always have the problem of having too many ideas for stories and before i can finish one i start the next one. i have come up with over 30 different ideas/plots for novels since i was 11. to get ideas for novels i look at other media. find what you love and dig deeper into it. for example, i have found that i love writing books with a social comment in them. something simple that makes people think. so i read things like orwells 1984, animal farm, utopia by thomas more, lord of the flies by william goulding, brave new world (which i have yet to read). so it really just depends. what genre are you interested in (eg fantasy, romance, horror) and what age group did you want the main readers to be (eg child, young adult or adult)??? and gender is important also. u dont want to write a love story for a guy, cos it will be kinda challenging.
i get inspired by listening to music or seeing something on televison and feeling like i could do a better job then them. What are u interested in? Whatever it is write down some topics about it and see which one you like the most.
The best person to come up with the idea is - YOU. You have to be passionate about the subject you are writing about. List 5 things that you are passionate about on a piece of paper. Then look at each subject and determine whether or not it fits with the current issues or trends. Example. If you live in the US and have a passion about eating healthy, you may want to write about how companies strive for profits are affecting the quality of our food - from rat feces infected peanut paste to the oil spill in the gulf affecting the seafood etc.
You have to start with a subject - what do you want to write a book about? A lot of books have already been written, so make yours something special.