When you are designing your self-published book the questions of which font to use and which font size are important ones. A good font can be one of the reasons why a reader picks up your book in the first place. You need your book to be legible and easy to read. It may be necessary to use different fonts / typefaces for different formats.
Every basic word processing program has an array of fonts and many more are available online. However, not all of them work well on eReaders or in print. The most popular fonts seem to be Times New Roman, Arial and Comic Sans but there are others out there which work for readers as well.
Thanks to computers one of the most popular fonts is Times New Roman. Obviously Times New Roman was designed for the Times Newspapers in the days when newspapers used narrow columns and small font sizes because print and paper were expensive commodities. It was nice, clear and elegant even in small type. Another popular font for word processors is Arial. Arial is a version of Helvetica, a popular font of yore. Helvetica is a clear font without any serifs so it looks clean on the page and is easy to read. As such it is a popular choice for road signs and companies. Arial itself is easy to read and good for people who are not good readers as it is a sans serif font.
Personally, I think Times New Roman is too squashed up with not enough kerning or letter spacing for a modern print book. I use Arial a lot for work publications but I am not sure I would like to read a whole book in it. The original Garamond is a little too fussy for me and I am not fond of serif typefaces. I am not sure it would work on an eReader either.More modern versions seem cleaner and clearer.
Usually I work in Bookman Old Style font which was very popular in the 1960s and 1970s. It has wide characters and lower case letters are 3/4 of the way up the upper case letters giving it a nice look on the page. The letters look clean on the page as each letter is balanced with kerning which makes for uniformity. However, I have been looking at Granjon which derives from Garamond. It was the font used in Patti Smith’s M Train with a nice line spacing where it worked well. I am not too sure how it will work with literary fiction though as it is a lighter weight font. Similar to Bookman Old Style is Palatino Linotype. In Palatino the letters are more chiselled and the foot of the letters is shorter so the typeface seems cleaner on the eye.
If you are interested in learning more about fonts and typefaces I have found the following article useful: Picking Fonts. For information about typography I recommend an article by Janie Kliever which is where the illustration below comes from.