What an amazing improvement! What was your secret, besides lots of practice?
For me, I think the greatest thing was approaching learning roundhand as re-learning how to write and so questioning and potentially changing everything that I did with respect to writing: I read and re-read 18th, 19th and early 20th century penmanship books which dealt with roundhand and practised only from the exemplars in those books. I changed how I held the pen, sat in my chair and put the paper before me (People often had their paper straight before them, not at a slant). It is not the work of a day, a week or a month, and I still carefully monitor how I sit and hold the pen, but it started making a difference. I also started using a straight penholder instead of an oblique, and not any straight penholder but a very slim one with a metal clasp just as you see in the New Spencerian compendium, for example.
Another thing was systematic practice from the large list of words given for penmanship practice here:
http://books.google.co.uk/books?id=BmsUAAAAQAAJ&dq=carstairs%20writing&pg=PA105#v=onepage&q&f=falseI'm still working my way through that list. Once I've gone through it at 8mm, I'll go through it at 6, and then 3.
Another thing was carefully studying the letters, especially the turns at the heads and tails (tilting hand to the left or right brings on great changes in how and where the shade thickens) and the proportions and parts of the capitals, and trying to imitate exemplars as exactly and faithfully as possible. I make great use of tracing paper: I trace my exemplar on tracing paper, write at the same size as it and put the tracing paper over my writing and can instantly seen any deviations. Checking slant with a protractor and going over a page with a pencil and ringing all errors and then re-doing the page was another important thing.
Another thing was practising on blank paper and ruling the lines using a drawing board, 0.3mm mech. pencil, t-square, and adjustable triangle for the slant lines. Trains the hand and eye and serves as a warm up and I find it easier to concentrate on writing when I don't have to search out guidelines peeping through the fibers of the paper as when a guide is placed beneath. And, If I wish the absolute finest of guidelines, I can use a 6H 2mm leadholder, appropriately sharpened to rule them.
Another thing was using only iron-gall ink and throwing away pens as soon as they begin to scratch or become worn and the line thickens. The more I have practised the longer pens last and the smoother they seem as I have become better at using them.
I think those are probably the most critical things, which worked for my improvement over several years, and hopefully for much more improvement.
