Reddit mentions of The Italic Way to Beautiful Handwriting: Cursive and Calligraphic

The short answer is to practice. But don't practice to the point of burning yourself out. Practice with a purpose. Work on a specific stroke or letter form at a time.

I found this book to be the most helpful.

In the sidebar is Handwriting repair: The italic approach.pdf for something free/crash course. I just purchased The Italic Way to Beautiful Handwriting: Cursive and Calligraphic by Fred Eager to start learning Italic Cursive myself.

All that training was needed for endurance writing. Now that we don't write very much simple practice with a modern pen on lived paper will improve penmanship enough.

I recommend something like this The Italic Way to Beautiful Handwriting: Cursive and Calligraphic https://www.amazon.com/dp/1626540381/ref=cm_sw_r_cp_apa_wnnPBbZMBD6XG

Fred Eager's seminal work is the definitive volume on the subject. https://www.amazon.com/Italic-Way-Beautiful-Handwriting-Calligraphic/dp/1626540381/ref=pd_sim_14_1/132-2624008-7086028?_encoding=UTF8&pd_rd_i=1626540381&pd_rd_r=6c27233e-6fa2-11e9-9f57-c98fbdd56605&pd_rd_w=LVDc1&pd_rd_wg=Sv8Vs&pf_rd_p=90485860-83e9-4fd9-b838-b28a9b7fda30&pf_rd_r=MTCV5R5Q65CA0Y0B5KQX&psc=1&refRID=MTCV5R5Q65CA0Y0B5KQX