1) You have to respect the time of the customer. Usually when a customer buys an information product off the internet rather than in a bookshop is because he or she wants a quick solution.
2) A quick solution is ideal to the customer. A lot of internet marketers make the mistake of making their information products, be they e-books, audio files or video programs as long as possible. It may be suitable for an extended e-course, but for normal solution based information products, do not make your products lengthy. Long documents and e-books may seriously turn your customers off. You may think that putting on your sales page that your product is 250 pages long, and is really worth the money for so much information. Look at it from a macro perspective: Do your customers really want to spend a week wading through your e-book to learn of the complete solution to their problem?
3) Make your e-book as efficient as possible in facilitating the customers' learning journey. Proper organization, a quick summary, action plans, and links to more resources will make them more efficient.
Keep length of e-books to about 30 pages on average.
Once again, let me reiterate that customers have very little time on their hands. So, help them to save their time by making their learning journey through your e-book as smooth, efficient and effective as possible. The whole internet marketing game takes time to master, so learn from those who have been there to shorten your learning time, and avoid painful mistakes.