@Naphthalene indeed, it’s becoming my favorite topic
I think a local class is your best bet to see if you actually like it or not first.
I tried to mix a long trip to japan with an introduction to Shodo course cause it felt logical at the moment. .
Now with only a few weeks left of that trip and after taking an introductory course in japanese for about 3 months (which I must say was a big leap of faith on my behalf still beginning to talk), I think you’ll benefit the most covering the basics probably in your own language, since I feel is where the most essential explanations are a must and be able to quickly get them will allow you to move freely with another resources (or even mix it with japanese ).
If you can play a bit with different resources (ball point pen, small brush, big brush, etc) the better. If not for the course I would never had thought that ball point pen and handwritten style was such a nice topic too (and probably the one with the most application to daily activities).
I think after a basic course, picking up a book with samples it’s a great idea. I’ve picked books in japanese that I’ll be taking with me, and overall I feel I have tons of material to improve with just that.
The books aren’t so full of text that will be like that wall of kanji experience you can face when approching to novels or other books, so I feel reading the explanations even if it takes more or less to get them could provide a well of material to keep improving (most books break the explanations in 1-2 pages, so I think if you can read simple material and don’t mind looking a bit most foundational books will be ok).
It’s more or less the same in any medium, characters are devided by the shape and mostly you learn how to writte the radicals and then are presented with example characters that share that pattern.
I picked up this book (which was basic enough covering different styles and comes with a DVD) and then this reference course a more detailed explanation on big brush (Kaisho style, the one you usually see).
Other on which turned pages in the library were this one (also a in depth course, from zero to hero style) and this other one, more like a sample book , with some notes on important points and common mistakes for individual charactes.
With a basic introduction and a reference material you can use sites like this one
Actually a google search with the words 書道 (Shodo) + 手本 (model) or 臨書 (writing model) will bring similar resources too.
This one will generate you own models for you to print them and you can choose Kaisho or Gyousho styles. Also you can then check the reference book to judge you on the main points of the character (or take it to your sensei of course).
If you care to have the school experience, you can also watch the NHK Kokokoza Shodo series … it has the video lessons and a lot of pdf’s to do the same activity they do in the “class” at home. (also it’s free).
Anyway, there are lots of videos on Youtube too, most are somewhat unorganized, so I can’t really pick one above the others.