A book? Good luck with that since its not an easy task. However my tips will be based on what kind of book you are writing - Is it a book, or some kind of research, etc.
Fiction books is what I like to write. This book that I want to write is titled "The Diary of the Lost" all I have thought of so far is it is going to be this girl who gets this diary and writes in it, everyday about her day. Later on down the road she goes on a cruise with her friend, but a storm crashes the ship, and most people but her get away. She however, washes up on a desterted island with her diary and has to survive (I havent thought of a period of time yet) by herself and only the wild animals for company. I wanted it to be in diary format.
Also if anybody has any great ideas that you think I should add to the book, please say so. Names, places, etc... All fictional.
Also remember to spellcheck often, use different adjectives to keep it interesting and try to imagine yourself in the characters position.