Reddit reviews Carta Manuscript Paper No. 9 - Basic

Read. This book is not great, but it's decent if you're coming from zero and you can put it in your pocket.

Get a manuscript notebook. This one is pretty good. Copy out examples and exercises.

Go to Bach's page on IMSLP. Find some solo pieces. Copy them out in your shiny new notebook. I suggest the cello suites, the two-part inventions, and the Well-Tempered Clavier. I chose these because they have great counterpoint and rely heavily on Fortspinnung (and so should you). Maybe you'll pick up things from paying close attention while copying. Make your notation look as close to the original as possible so you pick up good notation habits too, and get a good eraser.

I know that all this notating by hand does not seem very productive on its face, but trust me that it pays off. It will make your reading better and you'll become familiar with the structure and logic of music.