Don't forget headings when you decide on your text design. Normally, heading are in a different type to add contrast and interest to the page. Remember that too many different types can be confusing to the reader. If you stick to one larger, bolder type in the same family as your main type, your book will have more visual contrast and will keep the reader turning the pages to find out more information.
*Too many headings will break up the pages too much so don't get too crazy when you add headings.