If your goal is to write and sell an eBook, take a closer look at all of the online writing you are doing on a regular basis. Articles and blog posts will give you the content to fill up your eBook, but they will also serve as a means to market your eBook once it has been written.
As you are working on completing your eBook, take an excerpt from each chapter and turn it into articles and blog posts. This is a means of repurposing what you have to say into different formats that will attract different people. These articles, along with your blog, will serve to increase your visibility and credibility on the internet at the same time.
Then, go a step further. Write something on Facebook about what you are writing about in your eBook. Better yet, start your own group on Facebook and let thousands of people have the opportunity to find out more about you. Then, join Twitter and tweet about your niche topic. Topic tweeting will bring you more prospects because many people are searching by keyword there and will find you very easily.
The idea is to write about your niche so that your target audience can find you in a variety of ways through various mediums. In just a few weeks, you will be amazed at how many people will have connected with you online, hungry to find out more about what you have to share.