I am starting with Introduction to the Art of Modern Calligraphy (Calligraphy I), which is taught by Molly Jacques. I've only viewed the introductory videos so far, since I am still waiting for my class materials to arrive. However, I thought I would post a link now in case any of you want to join me.
I'll also write a more in-depth review once I've completed the class.
If the calligraphy class is not a fit for you, Skillshare offers many other lettering courses as well, including classes by well-respected letterers like Jessica Hische and Jon Contino. I'm not ready for the big leagues yet, but maybe you are.