I have sworn off. calligraphy "how to" books. -- as most do not truly address the problems of left handedness. I started looking at the books in the library and found a paucity of materials --- until I opened the new computerized card files and found every book with great examples and technique had been moved to the Art Museum's library downtown.
A wonderful member here gifted me a set of script practice manuals sending them through Amazon -- and some specially ruled paper which has helped immensely. He has encouraged me on line and through correspondence (I am jealous of his fluid script in correspondence and remain too embarrassed over my own writing to answer via post. But, the time will come when I will but stamps and send a better thank you note to him in my own hand than my on-line gratitude.
SO, if you have a pen club nearby, or calligraphy class/group with real people and a few examples of what you think you need to do -- the next step, to me, is to dive in with pen (inked) in hand and get started, analyze what you do not like when started, look at your examples, and figure out how YOU will make the pen move the way that lets you emulate when you want to he the best writing you will achieve.
Or, if you are of a mind, some of the basic cursive manuals purchased or on-line have exercises for using with up and down strokes, spring -link circles and similar exercises that will aid in making real consistent letters. I have not had the patience to use these, but they may help.
I ave found that books from the 1800s and early last century have some good ideas -- but are pretty wordy and even stodgy in making their spefic systems work.