First, you need to work out what you want your readers to feel. What are the emotions that your book should inspire and when? How do your characters feel during the story?
Second, think about a time when you've felt that way. Describe it! Use your own experiences to make your story better.
Third, remember your characters aren't you. How might they be different to you - what would they do that you wouldn't? What might they not do that you would?
Fourth, try to show your readers rather than just show them. Different emotions will have different effects on a person. When you are happy you might smile. When you're really sad you might physically shake. When you're excited you might be bouncing on the tips of your toes.
Fifth, choose your words carefully. Some words are more emotion provoking than others. Choose words that will hit home, that will evoke something inside your readers. How? Use what affects you. If it makes you cry, it will probably make someone else cry. If it makes you laugh, it'll make someone else laugh. But just to be safe, test it on someone else. See what their reactions are.