If you are planning to write an ebook as an epub format, you might consider choosing a native font that iBook app use.
When I made my first ebook I used font Tahoma, but I realized when I uploaded to ipad, it looked a bit strange.
So I end up changing the font in the entire document with Palatino font that iBooks app using.
If you are creating your ebook with Pages, you can specify the font for entire document.
You can also change the default font in Pages.
How to change default font in Pages?
To change the default font from Helvetica to any other font such as Times New Roman
1. Open a blank document
2. Type anything
3. Highlight the typing
4. Change the font to Times New Roman
5. Then Redefine Style
After redefine all the heading, title, body style save the document with a new template name.
You may also need to change the font for the list & character styles.
You should save the document by choosing save as template option.
Then you can make this template to your default document.
You may read iBooks app info at their website: http://www.apple.com/ipad/built-in-apps/ibooks.html
If you are using HTML based program to create your epub, here is the sample CSS code for the font:
font-family: Baskerville, “Times New Roman”, Times, serif;
You may review the iOSFonts.com website for whole list.
iPhone and iPad support @font-face embedding with SVG fonts.
iPad iBooks app uses epub and pdf format. PDF can have more font embedding.
However only epub format books allow the user (reader) to change fonts from the Font option.
Readers can change size and font types in iBooks app.
PDF books or documents do not allow the user/reader to make font changes.
I do enjoy using Georgia and Verdana on the web, they both look clear, sharp and nice.
However I avoid using Georgia if the text has too many numbers in it.
Numbers in the font of Georgia is a little uneven.
I added photo of the Georgia font with the size 14, regular how it looks on a page.