I think only the contents of the e-book are not sufficient, it must be user-friendly. So it’s better to use some interactive tools (Like Microsoft® HTML Executable). I think it’s better not to use MS Word or PDF writer.
It’s better to use some GIF image/some small animations to increase the interactivity. For this you can use some software like GIF animator, Swiss etc.
I think title is vary important in an e-book. Figure out your e-book’s working title. Jot down a few different titles, and eventually, you'll find that one that will grow on you. Titles help you to focus your writing on your topic; they guide you in anticipating and answering your reader's queries. Many non-fiction books also have subtitles. Aim for clarity in your titles, but cleverness always helps to sell books.
Write out a thesis statement. Your thesis is a sentence or two stating exactly what problem you are addressing and how your book will solve that problem. All chapters spring forth from your thesis statement. Once you've got your thesis statement fine-tuned, you've built your foundation. From that foundation, your book will grow, chapter by chapter.
Your thesis will keep you focused while you write your e-book. Remember: all chapters must support your thesis statement. If they don't, they don't belong in your book.
Once you have your thesis, before you start to write, make sure there is a good reason to write your book. Ask yourself some questions:
1. Does your book present useful and relevant information?
2. Will you book positively affect the lives of your readers?
Is your book dynamic and will it keep the reader's attention?
Does you book answer questions that are meaningful and significant?
If you can answer yes to these questions, you can feel confident about the potential of your e-book.
Another important step is to figure out who your target audience is. It is this group of people you will be writing to, and this group will dictate many elements of your book, such as style, tone, diction, and even length. Figure out the age range of your readers, their general gender, what they are most interested in, and even the socio-economic group they primarily come from. Are they people who read book reviews? Do they write letters in longhand or spend hours every day online. The more you can pin down your target audience, the easier it will be to write your book for them.
Make a list of the reasons you are writing your e-book. Do you want to promote your business? Do you want to bring quality traffic to your website? Do you want to enhance your reputation?
Then write down your goals in terms of publishing. Do you want to sell it as a product on your website, or do you want to offer it as a free gift for filling out a survey or for ordering a product? Do you want to use the chapters to create an e-course, or use your e-book to attract affiliates around the world? The more you know upfront, the easier the actual writing will be.
Decide on the format of your chapters. In non-fiction, keep the format from chapter to chapter fairly consistent. Perhaps you plan to use an introduction to your chapter topic, and then divide it into four subhead topics. Or you may plan to divide it into five parts, each one beginning with a relevant anecdote.
Also I would like to suggest some tricks to make the e-book user friendly.
You must figure out how to keep your writing engaging. Often anecdotes, testimonials, little stories, photos, graphs, advice, and tips will keep the reader turning the pages. Sidebars are useful for quick, accessible information, and they break up the density of the page.
Write with a casual, conversational tone rather than a formal tone such as textbook diction. Reader's respond to the feeling that you are having a conversation with them. Break up the length and structure of your sentences so you don’t hypnotize your readers into sleep. Sentences that are all the same length and structure tend to be aid.
In an e-book that is read on the screen, be aware that you must give your reader's eye a break. You can do this by utilizing white space. In art classes, white space is usually referred to as "negative space." Reader's eyes need to rest in the cool white oasises you create on your page. If your page is too dense, your reader will quit out of it as soon as their eyes begin to tear.
Make use of lists, both bulleted and numbered. This makes your information easy to absorb, and gives the reader a mental break from dissecting your paragraphs one after the other.
Finally, decide on an easy-to-read design. Find a font that's easy on the eyes, and stick to that font family. Using dozens of fonts will only tire your readers out before they've gotten past your introduction. Use at least one and a half line spacing, and text large enough to be read easily on the screen, but small enough so that the whole page can be seen on a computer screen. You will have to experiment with this to find the right combination.