The way you format your ebook will make a difference in how it sells. About half of the people who purchase your ebook will read it on their computer and the other half will want to print it out. This means that you must make it acceptable for everyone and easy to read.
Use a font that is easy on the eyes and universal to the majority of computers. Arial and Times New Roman are the two that will be the best to choose from. Use a font size of at least 12 but no larger than 14 for the bulk of the writing. Your headlines and sub-headlines will be larger to set them apart. You will want to use the headline feature when you write your chapter titles and subtitles so that you will have a table of contents when you convert your ebook to PDF. This makes it easier for people to navigate, especially if your ebook is more than one hundred pages long. Highlighting text is alright, but do not use red. Red highlighting is almost impossible to read and will just annoy your readers.
Pictures and graphics will make your ebook more appealing to the reader. Make sure you are using royalty free images so you do not run into any copyright issues.