Carving as we know it here as an art form is very different from other aspects of art, yet still has base elements of design: repitition of form (some sort of repitition), contrast, continuity for flow and design to stay out of dead spaces (golden means).
The carving you ask of is a 'C' scroll or an 'S' scroll or a combination of the two. Thickness of line is an expressive element that denotes emotion. A straight line is the most boring design element on the planet because once you see it, it is there and lends nothing to the imagination. A curving or dashed /broken line or the hint of line is more exciting. A straight line used as a border works, but used in conjunction with other elements is exciting. Thick to thin lines are great, they are always changing. Changing the thickness and thinness of lines (a graceful curvey line) is good, if it is so even, it becomes expected and then the viewer knows what's comming: making a subtle change and vary the line and it is now exciting. The design idea is finicky: keep it simple, yet keep it continuous, yet keep a contrast and have some repetition and try to have it designed in such a way that it meets the golden means demand.
Drawing means muscle memory which means practice, practice, practice, practice and some more practice. Take the book of drawings you have and try to repeat what you see and keep practicing. Eventually you may get real good, you may be okay or you may not. Just doodle some basic shapes at first, scrolls, figure eights, circles, wavy lines, then start putting them together.
Sometimes when I look at original carvings and engravings I often think what gracefullness.....it is clean graphic design, lack of clutter, says more with less and allows for interpretation. Then I think, what school of design did they go to? To be honest, some people have it and some don't.
Just my opinion.