Choosing a title for your ebook is the single most important task you will have. A great title will not make a poorly written book sell forever, but a poor title will hide your book from thousands of potential readers. Give much thought and consideration to the title and subtitle so that your book is adequately described.
You may want to give your book a working title while you are first writing. During this time you can test out your title choices in various ways. If you already have a list of people interested in your ebook topic, ask them to choose a title from several choices you have narrowed down. Also, research titles on Google and Amazon. You can even give people you know a list of two or three titles and ask them which ones they prefer. Dan Poynter, of Para Publishing, discusses titles at length on his site.