Hi Ashok,
Really great improvement in your work. I consider myself a beginner too, but I shall tell you what I was told for practise.
Like Salman rightly said, basic shapes need lot of practise. Ovals, and ascender/descenders are crazy always.
I use the following to do my daily practise. I try to get the x height to about 8mm, this really shows off the mistakes immediately.
Words I use are " cooking, hillbilly, minimum, saudade, little, - Schwarzkopf vexed Iraq big time in July "
Now if you really want it to be perfect, Do what Dr.Vitolo suggested. Write words like cooking and little. Then cover the top half of the x height with a paper, the bottom half curves should all be equal and the same.
The picture below is buy writing from 2 years ago, I still have not managed this
Did not want to put Dr.Vitolo's image on here so put mine. Should give you an idea of what I am talking about.
This was the main advice I received. "Focus on words, if you write full pages, you are concentrating on the text matter like spelling and stuff and not on the alphabet formation."
Hope that helps
Can't wait to see your work with the walnut ink too. You should be getting that in a day or two for sure
-Prasad