How does one make curves proportional in a font?


At some point I learned about trying to make strictly horizontal and vertical handles with my beziers, wherever possible. And I avoid unnecessary points... e.g. a perfect circle ought to be four points.

When I open other people's fonts, particularly scripts, the curves look so perfect. Like someone took a circle or ellipse and then chopped it half (or wherever). Or maybe did the equivalent of drawing a stroke in illustrator and outlining it.