How the Ballpoint Pen Killed Cursive

(2015)

The book he mentions, Teach Yourself Better Handwriting by Rosemary Sassoon is very good. Most handwriting books give you a model to copy, but her focus is on analyzing and improving your natural handwriting.

It is typical for people to see their handwriting improve upon switching to a fountain pen. I believe this is because a fountain pen encourages you to hold it so that the strokes to make good letter shapes come with less effort.