Five serif techniques

This illustration comes from Learn Calligraphy

As it says above, "calligraphy written with a pen usually has a serif."  But what kind of serif?  Here are five basic categories to choose from, each one illustrated in the text.  

Note small differences; they are what the eye sees even when the brain doesn't notice.  And try these serifs on other letters such as Bookhand.  Just stick with the same serifs throughout a page.