IMHO if you really want all the essential tips on how to construct italics, you should invest in
Foundations of Calligraphy by Sheila Waters - available from
John Neal Bookseller.
It is $35 (free shipping in the US) but you get detailed information on italics and variations. Sheila is not only a master of broad edge, but she is a master at teaching. John Neal deserves a ton of credit for publishing this book.
Besides italic, you also get foundational, blackletter, gothic cursive, uncial and half-uncial, carolingian - and variations. There are also chapters on analysis and practice, design and layout, and more. It is the most comprehensive, well-written and illustrated book you can imagine for broad edge. There is much more than what I have listed here. Your first attempt shows that you have good skill at replicating what you see. If you take time to self study with Sheila, you will be very pleased with the results. There are so many subtle details to broad edge, it would be very difficult to get the information you need from following one or two exemplars (with no explanation) and getting random bits of advice from the forum.
I agree with Erica that broad edge is *less forgiving* than the script styles. With scripts, you can do quirky, non-traditional writing and add some flourishing and it can be charming. With broad edge, there are people who do wild, contemporary variations (Luca Barcellone
http://www.lucabarcellona.com/ ) But, if you look at his work, you can tell that he mastered the traditional forms before he cut loose.
Sheila Waters has a section on How to practice followed by How NOT to practice -and- How to avoid calligraphic depression. That section -along with how to analyze- really explains the nuts and bolts of how to make progress with self study. Even if you have no interest in broad edge, that section (along with the 3 chapters on design, layout, and how to complete actual projects) is worth the price of the book.
