This email is from Pentsok Whenggyel Rtsang after the talk The Evolution and Great Diversity of Tibetan Scripts.
Dear All,
Thank you for taking the time to attend my talk.
If you are receiving this email, you have expressed interest in receiving some Tibetan calligraphy exercise books.
I am attaching two books and two links. The books contain manuals for many styles, including Uchen. And the links contain multiple calligraphy exercise books for mostly ume (you should start with the bottom one and make your way up when learning).
The order of learning should be from Tsugring (Tall Style), Tsugthung (Short Style), Tsugchung (Small Style), then Tsumakhyuk (Semi-Cursive), and finally Khyuyik (Cursive). This follows the reduction of sizes from the largest to the smallest as well. However, the actual history of development is from Uchen, to Druma (later evolved into Drutsa), then Bardri (Middle scripts), and finally to Tsugdri, which are the ones mentioned above.
The result of the letters also largely depends on the pen you use to scribe them, so it is important to have a big, flat-nibbed pen for starting. But for cursive and small styles, you can use a regular pen. I created a list on Amazon for your reference, in case you need to buy pens: https://www.amazon.com/hz/wishlist/ls/3AXVFB9MEL6AM?ref_=wl_share.
I am happy for your interest in learning Tibetan, and best of luck to you!